AS400 RPG400 Basics

Table of Contents: Chapter I :AS/400 Highlights..................................................................................7 Introduction :................................................................................................................................7 Technology-Independent Machine Interface ..........................................................................7 Operating System OS/400 .......................................................................................................8 Single-Level Storage ...............................................................................................................8 Logical Partitioning (LPAR) ...................................................................................................9 Objects.....................................................................................................................................9 AS/400 Processing Environment...............................................................................................12 What is a job?.......................................................................................................................12 Job Description:.....................................................................................................................12 Subsystem..............................................................................................................................12 Job Queues.............................................................................................................................12 Output Queues.......................................................................................................................12 Type of Jobs...........................................................................................................................12 AS/400 Security.........................................................................................................................14 Security at object level:..........................................................................................................14 Security Functions.................................................................................................................15 Security Levels.......................................................................................................................16 Application Development Tools (ADT)....................................................................................17 Program Development Manager (PDM)................................................................................17 Source Entry Utility (SEU)....................................................................................................20 Data File Utility (DFU)..........................................................................................................20

Chapter II –Libraries...........................................................................................22 Library Categories.....................................................................................................................22 Library List:..............................................................................................................................23 Library commands:....................................................................................................................23 Library List Commands:............................................................................................................23

Chapter III: AS/400 Database ............................................................................24 File Types:.................................................................................................................................24 Database Files:...........................................................................................................................25 Access paths:..........................................................................................................................25 Physical Files:........................................................................................................................26 Logical Files:.........................................................................................................................27 Types Of Logical Files...........................................................................................................28 Join Logical File....................................................................................................................28 Non - Join Logical File:.........................................................................................................28 Field Reference Files:................................................................................................................29 Importance of using Field Reference Files............................................................................29 Naming Conventions.................................................................................................................29

Chapter IV: Data Description Specification (DDS)...........................................31 Defining Physical Files..............................................................................................................31 Components of DDS..............................................................................................................32 Physical File Keywords.........................................................................................................33 File Level Keywords..............................................................................................................33 1 of 148

Record Level Keywords........................................................................................................33 Field Level Keywords............................................................................................................33 Key Field Level Key words...................................................................................................35 Defining Logical Files...............................................................................................................36 Logical file Keywords...........................................................................................................37 File Level Keywords..............................................................................................................37 Record Level Keywords ......................................................................................................38 Join Logical Files...................................................................................................................39 Join Level Keywords .....................................................................................................40 Examples of database files in DDS:...........................................................................................41 Example of a field reference file:...........................................................................................41 Example of a physical file with a new record format:...........................................................42 Example of a logical file specifying multiple formats and new keys:...................................43 Example of a logical file specifying a new record format:....................................................43 Example of a join logical file:................................................................................................44 DDM Files.................................................................................................................................45

Chapter V: SDA and Display Files......................................................................46 Screen Design Aid(SDA):..........................................................................................................46 Adding fields..........................................................................................................................48 Adding constants ...................................................................................................................48 Adding fields from a database file.........................................................................................48 Moving, Copying and Shifting fields.....................................................................................49 Date and Time keywords.......................................................................................................49 Display Files:.........................................................................................................................50

Chapter VI: RPG/400...........................................................................................57 RPG/400 Language Concepts....................................................................................................57 RPG/400 Specifications.............................................................................................................58 H CONTROL SPECIFICATION......................................................................................59 F FILE SPECIFICATION.................................................................................................59 E EXTENSION SPECIFICATION....................................................................................59 L LINE COUNTER SPECIFICATION.............................................................................59 I INPUT SPECIFICATION..............................................................................................59 C CALCULATION SPECIFICATION.............................................................................59 O OUTPUT SPECIFICATION.........................................................................................59 RPG/400 Operation Codes (OPCODES):..................................................................................59 Arithmetic Operations............................................................................................................60 ADD (Add Statement)......................................................................................................60 Z-ADD (Zeroise and add).............................................................................................60 SUB (Subtract statement)..................................................................................................61 Z-SUB (Zeroise and subtract)............................................................................................61 MULT (Multiply)..............................................................................................................61 DIV (Divide)......................................................................................................................62 MVR (Move remainder)...................................................................................................62 SQRT (Square root)..........................................................................................................62 Move Operations:...................................................................................................................62 MOVE (Move)..................................................................................................................62 2 of 148

MOVEL (Move left)..........................................................................................................63 Compare Operations..............................................................................................................63 IFxx (If condition).............................................................................................................64 DOUxx (Do until)..............................................................................................................65 DOWxx (Do while)............................................................................................................65 WHxx (When)....................................................................................................................66 COMP (Compare)..............................................................................................................66 Declarative Operations...........................................................................................................67 PLIST ( Parameter list)......................................................................................................67 PARM (Parameter)...........................................................................................................67 KFLD (Key Field).............................................................................................................67 KLIST (Key list)................................................................................................................67 DEFN (Definition).............................................................................................................68 TAG(Tag)..........................................................................................................................68 Initialization Operations.........................................................................................................68 CLEAR (Clear)..................................................................................................................68 RESET (Reset)...................................................................................................................69 String Operations..................................................................................................................69 CAT (Concatenate Two Character Strings).......................................................................69 CHECK (Check Characters)..............................................................................................70 CHEKR (Check Reverse)..................................................................................................70 SCAN (Scan Character String)..........................................................................................71 XLATE (Translate)............................................................................................................71 SUBST (Substring)............................................................................................................72 Subroutine Operations...........................................................................................................72 CASxx (Compare and execute subroutine)........................................................................72 EXSR(Execute Subroutine)...............................................................................................73 BEGSR(Begin Subroutine)................................................................................................73 ENDSR(End Subroutine)...................................................................................................73 Indicator Operations...............................................................................................................74 SETON (Set on indicator)..................................................................................................74 SETOF (Set off indicator)..................................................................................................74 Structured Programming Operations.....................................................................................74 ORxx (Or condition)..........................................................................................................74 ANDxx (And condition)....................................................................................................75 ELSE (Else).......................................................................................................................75 END (End).........................................................................................................................75 ENDyy (End Condition)....................................................................................................75 DO (Do Iteration)...............................................................................................................76 SELEC (Select)..................................................................................................................76 OTHER (Other)................................................................................................................77 ITER (Iterate) ....................................................................................................................77 LEAVE (Leave).................................................................................................................77 File Operations .....................................................................................................................78 OPEN (Open File for Processing)......................................................................................78 CLOSE (Close Files).........................................................................................................78 3 of 148

SETLL (Set Lower Limits)................................................................................................79 SETGT (Set Greater Than)................................................................................................80 READ (Read a Record).....................................................................................................80 READE (Read Equal Key)................................................................................................80 READP(Read a Previous Record)....................................................................................81 REDPE (Read Prior Equal)................................................................................................81 CHAIN (Random Retrieval from a File)...........................................................................82 WRITE (Create New Records)..........................................................................................82 UPDAT (Modify Existing Record)....................................................................................82 DELET (Delete Record)....................................................................................................83 Calling Operations.................................................................................................................83 CALL (Call a Program).....................................................................................................83 PARM (Identify Parameters).............................................................................................84 PLIST (Identify a Parameter List)....................................................................................85 Branching Operations............................................................................................................86 GOTO(Go to).....................................................................................................................86 ITER (Iterate).....................................................................................................................86 LEAVE (Leave).................................................................................................................86 Array Operations....................................................................................................................86 MOVEA (Move array).......................................................................................................86 XFOOT (Array Total)........................................................................................................87 LOKUP (Lookup)..............................................................................................................87 SORTA (Sort array)...........................................................................................................88 Data Area Operations.............................................................................................................88 Commitment Control Operations...........................................................................................88 COMIT (Commit)..............................................................................................................88 ROLBK (Roll Back)..........................................................................................................88 Examples For File processing:...................................................................................................89 RPG syntax to process an externally defined Physical File:...............................................89 RPG syntax to process a Program defined Physical File:...................................................89

Chapter VII: Subfiles ..........................................................................................91 Components of Subfile..............................................................................................................91 Subfile Data Description Specification : .................................................................................93 Handling Subfiles in RPG Programs.........................................................................................94 Multi page subfiles:....................................................................................................................95 Subfile Load Options- Pros and Cons....................................................................................95 Load all Subfile:.....................................................................................................................95 ...........................................................................................................................................96 Expanding Subfile:.................................................................................................................98 Single Page Subfile:.............................................................................................................100 Fold and Drop capabilities :.....................................................................................................102 Other interesting Subfile Keywords:...................................................................................103 Additional Recommended Reading Material.......................................................................103

Chapter VIII: Arrays, Tables and Data structures...........................................104 Arrays: ....................................................................................................................................104 Array Description :..............................................................................................................104 4 of 148

Loading of an array:.................................................................................................................105 Compile time array:.............................................................................................................105 Prerun time Array:...............................................................................................................106 Run time array:....................................................................................................................107 Searching Arrays......................................................................................................................109 Searching an Array without an Index..................................................................................109 Searching an Array with an Index.......................................................................................110 Specifying an Array in Calculations........................................................................................111 Tables :.....................................................................................................................................113 Data Structures: .......................................................................................................................113 Format of Data Structure Subfields in Storage:...................................................................113 Data Structure Statement Specifications:.............................................................................114 Examples:.............................................................................................................................115 Multiple Occurrence Data Structure:...................................................................................116 Data Areas :..............................................................................................................................117 Implicitly retrieved and written:.........................................................................................117 Explicitly retrieved and written: ......................................................................................117 Data Structures For Exception/Error Control..........................................................................119 File Information Data Structures (INFDS):.........................................................................119 Program Status Data Structure:............................................................................................120

Chapter IX: RLU and Printer Files...................................................................122 Report Layout Utility (RLU)...................................................................................................122 Report Line..........................................................................................................................122 Report Prototype..................................................................................................................122 Printer File Keywords..........................................................................................................122 Processing Printer Files in RPG Programs:.........................................................................125

Chapter X: Introduction To Control Language ...............................................126 Command Structure.................................................................................................................126 Positional Form....................................................................................................................126 Keyword form......................................................................................................................127 Both positional and Keyword form......................................................................................127 Command Continuation.......................................................................................................128 Variable naming syntax.......................................................................................................128 Concatenation......................................................................................................................128 Relational Expressions.........................................................................................................129 Logical Expressions.............................................................................................................129 Substring expressions...........................................................................................................129 Using variable in a CL program...........................................................................................130 Using files in CL program...................................................................................................130 File Operations.....................................................................................................................130 Error Handling.....................................................................................................................131 Assigning Values.................................................................................................................131 Logical Operations...............................................................................................................131

Chapter XI: Open Query File Basics................................................................133 Open data Path(ODP) : ...........................................................................................................133 QRYSELECT..........................................................................................................................134 5 of 148

Steps involved in a typical OPNQRYF program:....................................................................135 Example:................................................................................................................................135

Chapter XII: Message Subfiles in RPG............................................................136 Message Subfiles ....................................................................................................................136 Steps Involved : ...................................................................................................................136 Example :.............................................................................................................................137

Appendix A : RPG Opcodes.................................................................................142 Appendix B : AS/400 Data Limits.......................................................................147 Appendix C : RPG/400 Restrictions....................................................................148

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Chapter I :AS/400 Highlights

Introduction : AS/400 is designed as an entire system ,taking into account all the layers that were added to systems over last 30 years as we discovered one after another while the computer industry matured. Current mature operating systems were originally batch processors , many times patched to accommodate interactive and database use with many faster ,roomier drives. The user sees these systems today through various and complicated interfaces and paths. On the other hand , AS/400 design engineers created the layers of the onion from the outside in – the opposite of the design of older machines. First the functions that we all wanted, then user level interfaces that would make that function easy and accessible. Then the layers below those interfaces that would shield us from the intricacies of getting the function; finally a layered and queued system beneath the software in hardware(putting much software function of today into microcode). Paths among the layers were made standard and therefore movable and changeable. Technology-Independent Machine Interface The AS/400 is a typical in that it is defined by software, not by hardware. In other words, when a program presents instructions to the machine interface for execution, it "thinks" that the interface is the AS/400 hardware. But it is not! The instructions, presented to that interface, have to pass through a layer of microcode before they can be understood by the hardware itself. This design insulates application programs and their users from changing hardware characteristics through this comprehensive layer of microcode. When a different hardware technology is deployed, IBM rewrites sections of the microcode to absorb the fluctuations in hardware characteristics. As a result, the interface presented to the customer remains the same. This interface is known as the Technology-Independent Machine Interface (or TIMI). The microcode layer is known as the System Licensed Internal Code (or SLIC). The brilliance of this design was dramatically illustrated when the AS/400 changed its processor technology from CISC (Complex Instruction Set Computing) processors to 64-bit RISC (Reduced Instruction Set Computing) processors in 1995. With any other system, the move from CISC to RISC would involve recompiling (and possibly some rewriting) of programs. Even then, the programs would run in 32-bit mode on the newer 64-bit hardware. This is not so with the AS/400, because of TIMI. Customers were able to save programs off their CISC AS/400s, restore them on their new RISC AS/400s, and the programs would run. Not only did they run, but they were fully 64-bit programs.

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As soon as they made this transition, customers had 64-bit application programs that ran on a 64bit operating system containing a 64-bit relational database that fully exploited the 64-bit RISC hardware.

Operating System OS/400 One of the single most dramatic things about AS/400 is that its operating system, OS/400, is a single entity. This section describes the meaning of this concept. Once you buy an AS/400, you do not have to continue shopping for system software components before it is ready to run your business. All of those software components, for relational database, comprehensive security, communications with a broad range of diverse systems, including Internet capabilities, and many more, are already there. They are all fully integrated into OS/400 (AS/400 operating system). By "fully integrated", we mean fully tested, too. All those components, prerequisites for running business applications in the 1990s, work together and are fully tested together, so that OS/400 operates as a single entity. An ordinary machine does not have this approach to its operating system design. Single-Level Storage Just as application programs on an AS/400 are unaware of underlying hardware characteristics because of the TIMI. They are also unaware of the characteristics of any storage devices on the AS/400, because of single-level storage. As with TIMI, the concept of single-level storage means that the knowledge of the underlying characteristics of hardware devices (in this case, the hardware storage devices-- main storage and disk storage) reside in the SLIC. All of the storage is automatically managed by the system. Programs work with objects, and objects are accessed by name, never by address. No user intervention is ever needed to take full advantage of any storage technologies. The AS/400's address size is vast. Single-level storage enables another extremely important AS/400 benefit--object persistence.. Object persistence means that the object continues to exist in the memory system forever. An 8 of 148

ordinary machine requires that information be stored in a separate file system if the information is to be shared or if it is to be retained for a long time. Persistence of objects is extremely important for future support of object-oriented databases. Objects need to continue to exist even after their creator goes away. The AS/400 is uniquely positioned to exploit this characteristic of object persistence, where ordinary systems use a less-elegant mechanism that requires them to store their persistent objects in a separate file system, with all the attendant performance implications. Logical Partitioning (LPAR) As the performance of an enterprise class server grows, so does the requirement to divide that performance to run multiple workloads independently. Partitioning enterprise servers has become commonplace in the mainframe market since its introduction the mid-1980s. Typically, separate partitions are used for test releases of applications or to service multiple business units or companies from a single server. Logical partitions (LPAR) enable multiple independent OS/400 instances or partitions in an nway symmetric multiprocessing. Each partition requires its own processor(s), memory, disk(s), system console, with a CD-ROM and tape drive that can be allocated to each LPAR. With LPAR, you can address multiple system requirements in a single machine to achieve server consolidation, business unit consolidation, mixed production/test environments, integrated clusters, and more. Objects An object is a container. Everything the system uses--user and system data structures--is packaged in one of these containers. The objects are encapsulated, which means that you cannot see inside. Inseparable from an object is the list of valid ways in which that object can be used. All objects are structured with a common object header, and a type-dependent functional portion. Therefore, on the AS/400, instructions can only work on what they are supposed to work on. You cannot have data treated as executable code (so that the processor tries, for example, to execute someone's shoe-size), or executable code treated as data, (by having something written into the middle of it). Certain instructions apply to all objects, while other instructions work only on specific types of objects. It is not possible to misuse an object, unlike the situation that exists other systems without an object-based approach. There are two important consequences of an object-based design. The first is that a system built around an object model supports machine independence. This means that technology changes can be made in the environment without affecting application programs. The second consequence is that an object-based design delivers a high level of system integrity. Components of an object • •

Name –Generic name Library- that which contains addressability to the object

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•

• • • • • • • •

Type – attribute that defines the purpose of an object within the system. Each type has an associated set of commands that is used to process that object type. Attribute-An additional characteristic of an object within the object type. Owner-Name of the user who owns the object. Creation date /time. Save date /time. Restore date /time. Volume identifier for save. Free storage indication – Indication whether the object storage was freed when the object was saved. Size-Number of bytes allocated to the object in auxiliary storage.

Examples of Objects CMD Command Basic form of high level instruction to the system DEVD Device Description An information set describing the physical and logical attributes of a device connected to the system. DTAARA

Data area :

A data store

DTAQ

Data Queue

FILE

File

JOBD

Job desription Information describing environment in which a job would be executed

JOBQ

Job Queue Queue where the jobs wait for execution. JRN Journal:Object which controls storing of application data that needs to be recovered in case of a system failure. JRNRCV Journal Receiver:File in which application data that needs to be recovered in case of a system failure is stored. A journal receiver is always associated with a journal. LIB Library User defined place within the system where any particular group of objects reside.

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MSGF MSGQ OUTQ PGM

Message File A database file where messages are stored. Message Queue Queues where messages wait to be passed or displayed. Output Queue Queue where the system output waits to be viewed printed or transferred Program

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AS/400 Processing Environment What is a job? A job is the basic unit of work on the AS/400.Every activity on the AS/400 is done as part of a job. Each job is a single , identifiable sequence of processing actions that represent a single use of the system. Attributes of a job: Job number:The job number is a unique system generated sequential number Job Name :Job name is any user defined name. For certain jobs, the system assigns a job name which is usually the name of the corresponding job description. User Name:User name attributed with a job is the name of the user who initiated the job. The combined usage of the job number, job name and user name uniquely identifies a job in the system. Job Description: A job description is a collection of parameters that control the job when it is started in the subsystem. The advantage of using a job description is that once it is defined you can use it anywhere just by referring to the job description name whenever you want to start job. Subsystem A subsystem is single predefined operating environment in which the system coordinates the work flow and resources. Subsystems are specific user defined job partitions of the CPU where various jobs may be executed. The system is shipped with a set of IBM supplied subsystems which may be modified if required. One subsystem may have more than one job active at a time. Job Queues Job Queues are streams where jobs wait for execution. Job queues are attached to specific subsystems. One subsystem may have more than one jobq attached to it. Output Queues Output queues are streams where output from the jobs wait to be processed. It is a place to hold the output spooled files created by jobs.

Type of Jobs Interactive jobs:

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An interactive job starts when the user signs on to the machine and lasts until user signs off. A job is created by the system to interactively react to the users responses and thus is called an interactive job. Batch jobs: A Job is called a batch job when a series of actions submitted to a job queue for execution in one single job stream. Spooling job: A spooling job can be for input or output.In an input spooling job ,a system program called a reader transfers job from the input device such as a diskette or database file. For output spooling , the job puts the output from a program into a spooled file , later the spooled file can be written to an external device such as a printer. Autostart job: A autostart job is always associated with the subsystem , and whenever the subsystem is started the autostart job is started as well. Additional Recommended Reading Material : 1.SC41-8078-01 AS/400 Work Management Guide

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AS/400 Security The Security is unbreachable because it is not a layer added on top of an interface , which , after being unlocked provides complete access. Rather, it is a check built in every step the system takes for you (once again , with this system you only request work to be done for you , you do not actually do it yourself). It is built into both the hardware and the software and it has to do with function ,location, user type and type of use. On the AS/400 all information is stored in objects. Access to that information is through hardware instructions that ensure object integrity . Any attempt to misuse an object detected, causing the system to terminate the instruction and signal an exception condition. Security at object level: Object ownership: All objects have owners. Initially , the user who creates the object is the owner. However, the owner, the Security officer, or a user with Object existence rights can transfer ownership to another user. Public or Private authority over an object: Object use can be authorized privately or publicly. ‘Private’ means to specific users; ‘Public’ means to all users. Looking at Security from the object outward: The owner of the object has authority to do all things possible to it. • *ALLOBJ authority can be granted to a user , which gives this user ‘ all things possible’ authority. Now the grantee can further grant authority and revoke it as well, even from the original owner. • *PUBLIC authority reaches everybody and can be granted by the owner at some command level to all system users. Security over libraries can be defined at these levels: • *EXCLUDE – Users Can’t get it all(only the owner and security officer can use it) • *USE – A user can DISPLAY the content of the library ,use commands to find objects ,put the library in LIB list, and save the library. • *ALL- Users have all the object authorities and all the data usage level authority on the contents of this library on the library itself. Object Authority: Object authority is used to control access to an object including the ability to see an object description, control read and write access to an object, or control an object's existence. •

*OBJMGT : provides the authority to specify the security (grant/revoke object authority), move or rename the object, and add members to database file. 14 of 148

•

*OBJEXIST: provides the authority to control the object existence and ownership. The user with this authority can delete, save, and transfer ownership of the object.

•

*OBJOPR : provides the authority to look at the description of an object and use the object as determined by the data authority that the user has to the object.

Data Authority: Data authority is the authority to access data contained in an object, for example records in a database file. This includes the ability to view, update, add, or delete records. •

*READ :provides the authority to get the contents or an entry in an object or to run a program.

•

*ADD :provides the authority to add entries to an object.

•

*UPD :provides the authority to change the entries in an object.

•

*DLT :provides the authority to remove entries from an object.

Combinations of Object and Data Authorities These are keywords, each representing predefined combination of object and data authorities. They reduce the time required to assign specific authorities to users. *ALL allows the user to perform all authorized operations (object and data) on the object. *CHANGE provides *OBJOPR authority and all data authority. *USE provides *OBJOPR authority and data read authority. *EXCLUDE authority prevents the user from accessing the object even if *PUBLIC is authorized. In addition to these, users can create customized combinations of object and data authorities Security Functions Setting the security levels for the system The system can be set to various security levels. The system is shipped with a ‘minimum’ security level, which means that any user can sign on and use any data or programs on the system. If your system has more than just ‘minimum’ security officer controls, who has access to the system and its data.

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Security Levels The AS/400 system allows to select the level of security needed to use on your system. The different levels provide varying degrees of security, which are as follows: Level 10 The system is not secured. No password is required to signon. No resource security is used, so all users can access and use all system resources. Level 20 The system has limited security. A password is required to signon, but no resource security is used. All users can access and use all system resources. Level 30 The system is designed to be fully secured. A password is required to signon.Resource security is used , which means that system resources are available to users depending on what objects they have authority to use and what special authorities they have. Level 40 The system is designed to be fully secured, as it is for level 30.In addition, the system is protected from access by unsupported interfaces.

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Application Development Tools (ADT) Program Development Manager (PDM) Program Development Manager is a complete development tool which allows the programmer to perform all programming related activities under one single menu driven easy to use and comprehensive environment. Functions of PDM • PDM allows the user to work with the libraries and objects in terms of performing the following functions among others. ♦ Create ♦ Change ♦ Display ♦ Delete ♦ Rename ♦ Move • • • •

Work with members namely Edit / Rename / Clear / Remove Find strings, that is to find a character or string in a source or data file. Define Commands to perform repetitive actions on objects from a list Call the other Application Tools mentioned Below : Source Entry Utility (SEU) Screen Design Aid (SDA) Data File Utility (DFU) Report Layout Utility (RLU)

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Invoking PDM Program Development Manager can be invoked in any one of the following ways : 1. Take option ‘5’ for the programmers menu from the AS/400 main menu.Then take option ‘2’ for PDM from the programmer’s menu 2. Enter command ‘STRPDM’ from any command entry line AS/400 Programming Development Manager (PDM) Select one of the following: 1. Work with libraries 2. Work with objects 3. Work with members 9. Work with user-defined options

Selection or command ===>______________________________________________________________________________ F3=Exit F12=Cancel

F4=Prompt F9=Retrieve F18=Change defaults

F10=Command entry (C) COPYRIGHT IBM CORP. 1981, 2000.

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3. Enter command ‘WRKLIBPDM” – Work with Libraries in PDM – from any command entry line to work with libraries Work with Libraries Using PDM List type

. . . . . . .

Type options, press Enter. 2=Change 8=Display description

*LIBL

Opt -

Library RBTSYSLIB QSYS QSYS2 QHLPSYS QUSRSYS SYSTEM XCOM2 QMQM QSYS2924

Type *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS *PROD-SYS

3=Copy 9=Save

5=Display 10=Restore

7=Rename 12=Work with ...

Text ROBOT SYSTEM LIBRARY SYSTEM LIBRARY SYSTEM LIBRARY FOR CPI'S System Library for Users EHQ System Software CA-XCOM software library MQSERIES FOR AS/400

More... Parameters or command ===> ______________________________________________________________________________ F3=Exit F4=Prompt F5=Refresh F6=Add to list F9=Retrieve F10=Command entry F23=More options F24=More keys

4. Enter command ‘WRKOBJPDM” – Work with objects in PDM – from any command entry line to work with objects Work with Objects Using PDM Library . . . . .

TSTLIB

Type options, press Enter. 2=Change 3=Copy 8=Display description Opt -

Object XMSGDTARFP YABOABARFP YABOABAXXP YABOABA00L YABOABA01L YABOABA02L YABOABA03L YABOABA04L

Type *FILE *FILE *FILE *FILE *FILE *FILE *FILE *FILE

Position to . . . . . . . . Position to type . . . . . 4=Delete 9=Save Attribute PF-DTA PF-DTA PF-DTA LF LF LF LF LF

5=Display 10=Restore

________________ ________________

7=Rename 11=Move ...

Text MDL Message Physica yaboabarfp Physical fi Contains YABOABARFP deleted model dat MDL Abo update (@@ABOABA) MDL Abo action rtv (@@ABO/@@CHC/@@ABO MDL Abo action rtv (@@ABO/@@ABOABA_P) MDL Abo action rtv (@@ABO/@@REFCND > MDL Abo update (@@ABO/@@ABOABA) More...

Parameters or command ===>______________________________________________________________________________ F3=Exit F4=Prompt F5=Refresh F6=Create F9=Retrieve F10=Command entry F23=More options F24=More keys

5. Enter command ‘WRKMBRPDM” – Work with members in PDM – from any command entry line to work with members

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Work with Objects Using PDM Library . . . . .

TSTLIB

Type options, press Enter. 2=Change 3=Copy 8=Display description Opt

Object XMSGDTARFP YABOABARFP YABOABAXXP YABOABA00L YABOABA01L YABOABA02L YABOABA03L YABOABA04L

Type *FILE *FILE *FILE *FILE *FILE *FILE *FILE *FILE

Position to . . . . . . . . ___________ Position to type . . . . . _____________ 4=Delete 9=Save Attribute PF-DTA PF-DTA PF-DTA LF LF LF LF LF

5=Display 10=Restore

7=Rename 11=Move ...

Text MDL Message Physica yaboabarfp Physical fi Contains YABOABARFP deleted model dat MDL Abo update (@@ABOABA) MDL Abo action rtv (@@ABO/@@CHC/@@ABO MDL Abo action rtv (@@ABO/@@ABOABA_P) MDL Abo action rtv (@@ABO/@@REFCND > MDL Abo update (@@ABO/@@ABOABA) More...

Parameters or command ===>______________________________________________________________________________ F3=Exit F4=Prompt F5=Refresh F6=Create F9=Retrieve

PDM is terminated by pressing EXIT (F3) function key

Source Entry Utility (SEU) Source Entry Utility is a development tool that allows the entry, review and display of program source statements and date descriptions specification for various specification types. Functions of SEU SEU function is allow the user to: ♦ Create / add new members ♦ Revise existing members ♦ Browse / Copy the existing members SEU can be invoked through one of the following methods: 1. Select option ‘5’ from the programmers menu 2. Select option ‘2’ from the Work with members display in PDM to browse through the source members 3. Select option ‘5’ from the Work with members display in PDM to edit source members 4. Enter command ‘STRSEU’ from any command entry line.If the command is Invoked without a qualified member name, a list of all the members in the file is displayed.

Data File Utility (DFU) Data File Utility (DFU) is a development tool that allows the entry, revision and browse of data records from the database files. 20 of 148

Functions of DFU DFU functions are to allow for the creation of applications for the manipulation of data records. These applications can then be executed to manipulate data records. Manipulation of data records includes adding or inserting new records and changing, deleting or displaying existing records AS/400 security allows for the restriction of access to the selected files bound by the user Securiry. Additional recommended reading Material: 1. SC09-1338-02 SEU User’s Guide and Reference. 2. SC09-1339-02 PDM User’s Guide and Reference. 3. SC09-1340-02 SDA User’s Guide and Reference. 4. SC09-1416-02 RLU User’s Guide and Reference. 5. SC41-9614-03 AS/400 Query / 400 User’s Guide.

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Chapter II –Libraries

A Library is an AS/400 object that serves as a repository for other objects. It is not a parititioned data set but rather an index to other objects. The library can never become ‘full’ as it has no definite size. Generally a library can contain any set of objects grouped for a specific purpose.

Library Categories The libraries can be categorised ac IBM supplied libraries, user-defined libraries . IBM Supplied Libraries are: 1. QSYS Contains IBM supplied programs and data.This library cannot be deleted or renamed. This library is owned by system security officer. 2.

QSYS36

Contains objects required to run software developed on the System/36.The software would then be executed in ‘System/38 mode’.

3.

QSYS38

Contains objects required to run software developed on the System/38. The software would then be executed in ‘System/38 mode’

4.

QGPL

Contains IBM supplied objects for general use. This library is present in every library list unless explicitly removed.

5.

QTEMP

Created automatically for every job. The library hold temporary objects such as work files. This library can be accessed by the job that created it. This library would be deleted when the job is terminated.

6.

QSRV

Service engineer library.

7.

QRCL

Reclaim storage library .It is created when a Reclaim Storage command(RCLSTG) is executed and would contain objects that were purged by the command.

8.

QRPG

Report Program Generator library. It contains RPG compiler and the objects required to enter,edit and compile RPG programs.

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9.

QCBL

COBOL/400 library.It contains COBOL compiler and the objects required to enter, edit and compile COBOL/400 programs.

10. QIBU

Interactive data base utilities library.

11. QINS

Interactive workstation support library that contains all IBM supplied objects that are required to transfer data between AS/400 and PCs.

User-defined libraries These libraries are created by users for specific application and uses.User-defined library name may be use-defined alphanumeric name not more than 10 characters. Library names may not have embedded blanks and must not begin with a number.

Library List: It is a list of libraries associated with each job which defined the operational boundaries of a job. Each job has a default library list which may be modified if required.Each library list consists of four parts. They are: System library section - This section consists the libraries containing objects used by the system for regular processing functions. The number of libraries in this section cannot exceed 15. Product library section - This section contains libraries that are required to support high level languages and utilities other than QSYS. Current library section – This section contains the ‘current library’ as identified by the job. User library section – This section contains libraries required by system users and applications such as non-IBM application solutions.The number of libraries in this section cannot exceed 25.

Library commands: Common commands associated with libraries are: CRTLIB Create library DSPLIB Display library DLTLIB Delete library

Library List Commands: Common commands associated with library lists are: DSPLIBL Display library list 23 of 148

ADDLIBLE Add library list entry RMVLIBLE Remove library list entry RPLLIBL Replace library list CHGCURLIB Change current library

Additional Recommended Reading Material 1. GC41-9802-01 AS/400 System Concepts.

Chapter III: AS/400 Database In AS/400, the data base is integrated into the operating system and is the licensed internal code of the AS/400 system. There is no requirement to install or maintain a separate database management product. Any program that wants to store or use data on the AS/400 system uses integrated database

File Types: The different types of files that form AS/400 database ar 24 of 148

1. Database files are files (including distributed files) whose associated data is stored permanently in the system. i. Physical files 1. Data files 2. Source files ii. Logical files 2. Device files are files that provide access to externally attached devices such as displays, printers, tapes, diskettes, and other systems that are attached by a communications line. The device files supported are: – Display files, which provide access to display devices – Printer files, which describe the format of printed output – Tape files, which allow access to data files on tape devices – Diskette files, which provide access to data files on diskette devices – Intersystem communications function (OS/400-ICF) files, hereafter referred to as ICF files, which allow a program on one system to communicate with a program on the same system or another system 3. Save files are files that are used to store saved data on disk (without requiring diskettes or tapes). 4. Distributed Data Management files (DDM files) are files that allow access to data files stored on remote systems. Each file type has its own set of unique characteristics that determines how the file can be used and what capabilities it can provide. The concept of a file, however, is the same regardless of what type of file it is. When a file is used by a program, it is referred to by name, which identifies both the file description and, for some file types, the data itself. This information is designed to help you understand the common characteristics of all file types so you can use the files to their full capabilities.

Database Files: • •

The Object type is *file It contains description of how input data is to be presented to programs from internal storage and how output data is to be presented to internal storage from a program

Access paths: Arrival Sequence Access Path : • It is based on the order in which the records arrive and are stored in the file • Sequentially, where each record is taken from the next sequential physical position in the file • Directly by relative record number, where the record number is identified by its position from the start of the file Keyed Sequence Access Path: 25 of 148

• •

It is based on the contents of the key fields as defined in DDS This type of access path is updated, whenever records are added or deleted.

Physical Files: • A description of how data is to presented to or received from a program and how data is actually stored in the database • A Physical file contains one record format and one or more members Components of a Physical File • Object Header This contains the regular object information • Record Format Describes the format in which the records are stored • Access Path Describes the order in which records are to be retrieved • Data Member Contains data Data Description Specification for a Physical File: • File Level entries (optional): File level entries give the system information of the entire file including whether the key is unique • Record Level entries : Give the system information about the specific record format in the file • Field Level entries : The field names and field lengths are specified along with an optional text description for each field • Key Field Level entries : The field names used as key fields specified DDS Keywords: • File Level : Unique, LIFO, FIFO, FCFO, Ref • Record Level : Format, Text • Field Level : Alias, Reffld, Text, Edtcde, Datfmt, Datsep, Alwnull, Check(AB, ME, MF), Cmp/Comp, ColHdg, Dft, Range, Timfmt, Timsep, Values • Key-field Level : Absval, Descend, Signed, Unsigned Characteristics of a Physical File • Maximum no. of fields that can be defined in a PF is 8000 • Maximum no. of members that a single PF can have is 32,766 • Maximum size of a member in a PF is 32,766 bytes • Maximum length of a file name is 10 characters • Maximum length of a record format name is 10 characters • Maximum length of a field name is 10 characters • Maximum number of key fields in a PF is 200 View of a Physical File: File Level Record Level Field Level

R

Unique

Key-Field Level

k

Recfmt Name Age Phone Name

20 10 P 10 P 3

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Logical Files: • Logical File is an AS/400 object of type *file and attribute LF • Used to arrange data from one or more physicals into different formats and sequences • Logical file does not contain any data, but provides ‘VIEWS’ of the data to satisfy endusers’ needs • A logical file can contain up to 32 record formats and can obtain data from 2 to 32 physical files Components of a Logical File: • Object Header This contains the regular object information • Record Format Describes the format in which the records are stored • Access Path Describes the order in which records are to be retrieved • Data Member Contains Data Data Description Specification for a Logical File: • File Level entries (optional): File level entries give the system information of the entire file including whether the key is unique • Record Level entries : Give the system information about the specific record format in the file • Join Level entries : Give the system information about physical files used in JOIN Logical File (Not applicable for Non-Join Logical File) • Field Level entries : The field names and field lengths are specified along with an optional text description for each field • Key Field Level entries : The field names used as key fields specified • Select / Omit Level entries : Give the system information about, which records are to be returned to the program when processing the file DDS Keywords: • File Level : • Record Level : • Join Level : • Field Level Check(AB, • •

Unique, LIFO, FIFO, Jdftval(JLF) Jfile (Join File), Pfile (Physical file), Text Jdupseq, JFld, Join : Alias, Reffld, Edtcde, Datfmt, Datsep, ME, MF), Cmp/Comp, ColHdg, Dft, Range, Timfmt, Timsep, Values, JRef Key-field Level : Absval, Descend, Signed, Unsigned Select/Omit Level : Comp, Range, Values, All

View of a Logical File: Record Level Key-field Level

R PFRecfmt1 K Cust#

PFILE(PF1)

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Types Of Logical Files • Non - Join Logical Files • Join Logical Files Join Logical File • Join logical files are READ only files and may not be used in UPDATE or DELETE processing • Support only Inner and Left Outer Joins. Outer Join processing is not supported • They may refer 2 to 32 physical files • Any key field specified must be included in the primary file • Select / Omit criteria may be specified for any field in a Join Logical File Data Description Specification for Join Logical Files: • File Level entries • Join Level entries • Record Level entries • Field Level entries • Key Field Level entries • Select and Omit Field Level entries View of a Join Logical File: R Joinrcd J Enum Ename Dept K Enum S Enum

JFILE(PF1 PF2) JOIN( 1 2 ) JFLD( ENO ENUM ) JREF(1) JREF(1) JREF(2) comp GT 1010

Types of Join Logical File: There are 3 types of Logical Files 1. Natural Join or Inner Join : When this type of a JLF is read only the matching records of both the files appear 2. Left Outer Join : All the records from the primary file appear. Missing secondary records (records for which no match is found) are filled with default values. This is enforced by using JDFTVAL keyword 3. Self Join: Joining a file to itself Non - Join Logical File: • A Non-Join logical file can either be a simple logical file which contains only one record format or a multiple format logical file which contains more than one record format 28 of 148

• Non-Join logical files can be used for READ, WRITE and UPDATE processing • Can join a maximum of 32 Physical files • Data Description Specification for Non-Join Logical Files: • File Level entries • Record Level entries • Field Level entries • Key Field Level entries • Select and Omit Field Level entries Repeat steps 2 through 5 for each record format in the file View of a Non-Join Logical File: Record Level R PFRecfmt1 Field level Cust# Key-field Level K Cust# Record Level R PFRecfmt2 Field level Cust# Key-field Level K Cust#

PFILE(PF1) PFILE(PF2)

Field Reference Files: • •

A physical file that contains no data, but only description of fields. It is used as a reference for the field descriptions of other files

Importance of using Field Reference Files It enforces the naming convention • Reduces programmer’s work load (define once, use often) • It defines in one place all data elements used in the application for all users

Naming Conventions • • • • •

The file name, record format name, field name cannot be more than 10 character’s The first character should be alphabetic Field names should be unique in a record format Record format names and member names should be unique in a file File names should be unique in a library

Additional Recommended Reading Material 1.

SC41-9659-02

AS/400 Database Guide

2.

SC41-9658-02

AS/400 Data Management Guide

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Chapter IV: Data Description Specification (DDS) Data Description Specifications(DDS) defines all attributes of a file and which are coded in a system-defined format. These definitions or specifications can be maintained externally and independent of programs or other dependent files. These statements are entered into a system-defined format as a source file which is created or compiled as a file.Data records are then written into or retrieved from this file using certain Application Development Tools or though use-defined application programs. DDS are coded and entered into a system-defined format known as ‘A’ specifications. Each file is coded as a separate source member.’A’ specifications are used to code the following types of files.The positions and entries are unique and may differ for the different files.  Physical files. 

Logical files



Display (or workstation) files and



Printer files

Defining Physical Files The Data Description Specifications(DDS) for Physical Files are defined in data specifications in the following layout: Positions Name Entry Explanation 1-5

None

6

Sequence number Form type

7

Comment

‘*’

8-16

Reserved

Blank

17 19-28

Type of Name ‘R’ ‘‘ ‘K’ Name

29

Reference

‘A’

R

This is an optional column and may be used to identify, mark or tag source statements. Denotes ‘A’ Specification Denotes a comment line. Comments may be entered betweenpositions 8 and 80. This position Is not used for physical files and must be blank. Record format name. Field name. key field name. Record name or field name or key field name. Denotes that a definition and attributes of the named field are to be referenced from a previously defined field.

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Positions

Name

30-34

Length

35

Data Type

36-37

Decimal position Usage

38

Entry

P S B F A H L T Z ‘B’

Explanation Length of the field. The following are the valid lengths for various types of fields. Character 1 to 32766 Hexadecimal 1 to 32766 Binary 1 to 9 Numeric 1 to 31 Packed decimal Zoned decimal Binary Floating point Character Hexadecimal Date Time Timestamp. Number of decimal positions Both input and output Defaults to B

‘‘ 39-44

Location

45-80

Keywords.

This column is reserved and is not used by physical files.

Components of DDS DDS definitions are a serious of statement that are entered as source statements. These statements may be entered in to the following levels of definitions.  File level keywords are entered at the file qualify the named file and are applicable to all the record and field definition that follow.  Record format level keywords are entered at the record format level qualify the named record format and are applicable to all the field definitions contained within the record format.  Join level keywords are used to specify parameters that are used to join one or more files in to a single record format. These keywords are valid only in join logical files.  Field level keywords are used to qualify the named field.  Key field level keywords are used to qualify the key or the access sequence of a file. For example, UNIQUE can be specified to prevent existence of duplicate key values in a file.  Select/Omit level keywords are used to specify rules for the selection of records from a physical file, these keywords are valid only in logical files. Naming Conventions 32 of 148

The normal rule for naming of files, record formats and fields is a 10 character alphanumeric value which does not contain embedded blanks and does not start with a numeric value. However, some high level languages like RPG/400 supports only 8 character file and record format names and 6 character field names. Physical File Keywords Keywords used in physical files are vided into 4 parts. They are: File level Keywords Record level Keywords Field level Keywords Key-field level Keywords There are in all over 35 keywords associated with physical files.These keywords are used to provide further qualification to the file, record format, field or key field.Some of the more commonly used keywords are: File Level Keywords  FCFO First Changed First Out When duplicate key exists in a file this keyword is used to specify that the record that was changed earliest is to be retrieved.  FIFO First In First Out When duplicate key exists in a file this keyword is used to specify that the record that was written earliest is to be retrieved.  LIFO Last In First Out When duplicate key exists in a file this keyword is used to specify that the record that was written most recently is to be retrieved.  REF Reference Used to indicate the name of another file from which field references wherever indicated are to be retrieved.  UNIQUE Unique Key Used to indicate that records with duplicate key values will not be allowed in this file. Record Level Keywords  TEXT Text Used to assign descriptive text for the record format. Field Level Keywords  ALIAS Alias Name Used to indicate the alias name for the named field.  ALWNULL Allow Null value Used to indicate that the field may be written with NULL value (blanks for character fields and zeroes for numeric fields) 33 of 148

 CHECK Check values Used to provide certain validity rules for the named field.The values associated with this keyword are as follows: AB Allow blanks ME Mandatory Entry MF Mandatory Full M10 Modulus 10 validation M10F Modulus 10 validation(IBM variation) M11 Modulus 11 validation M11F Modulus 11 validation(IBM variation) Example, CHECK(ME)  CMP/COMP Compare Value Used to provide validation to specify that the named field must contain value specified in this parameter. Example, COMP(*EQ ‘A’)  COLHDG Column Heading Used to provide descriptive text about the named field. This text is used when the field is used in certain application development tools such as Data File Utility(DFU) and Query. Up to three strings of 20 characters each can be specified.  DATFMT Date Format Used to define the format (namely one of either, YY/MM/DD or MM/DD/YY or DD/MM/YY) in which date is to be stored in the named field.  DATSEP Date separator Used to identify the character used to separate the elements of a date.  DFT Default Value Used to nominate a default value when the record is written.  EDTCDE Edit Code Used to identify a system-supplied editing rule for the named field. Rules could include zero suppression, zero balance, sign etc.  RANGE Range Used to specify a range of values that are allowed to be input in to the named field.  REFFLD Referenced Field Used to reference a field from an earlier referenced file whose length and attributes are to be attached to the named field. REFFLD(FLDA) REFFLD(RECFMT01/FLDA) REFFLD(RECFMT01/FLDA FILEA) REFFLD(RECFMT01/FLDA *LIBL/FILEA) REFFLD(RECFMT01/FLDA LIBA/FILEA)  TEXT Text Used to assign descriptive text to the named field to be used in all future references of the named field. Example, TEXT(‘Customer code’).  TIMFMT Time Format Used to define the format in which time is to be stored in the named field.  TIMSEP Time Separator 34 of 148

Used to identify the character to be used to separate the elements namely hour,minute and second of time.  VALUES Values Used to assign one or more values that are allowed as valid input in to the named field. Example, VALUES(‘A’, ‘B’, ‘C’, ‘D’, ‘E’). Key Field Level Key words  ABSVAL Absolute Value Used to indicate that when retrieving records from the named file, the sign of the key field is to be ignored and only the absolute value of the field is to be used for purposes of ordering sequences.  DESCEND Descending Sequence Used to specify an ordering sequencing for the retrieval of records from the named file.when retrieving records from named file, the records would be sequenced in the descending order of the named key field.  SIGNED Signed Used to specify that the sign of the named key-field is to be considered for purposes of ordering sequence when retrieving records from the named file.

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Defining Logical Files The Data Description Specifications(DDS) for Logical Files are defined in data specification in the following.

Positions 1-5

Name Sequence Number

Entry None

6 7

Form Type Comment

‘A’ ‘*’

8-16

Conditioning

Blank

17

Type of Name ‘R’ J ‘‘ ‘K’ ‘S’ ‘O’

18

Reserved

19-28

Name

29

Reference

30-34

Length

35

Data Types

Blank

R

P S B F A H L

Explanation This is an optional column and may be used to identify mark or tag source statements. Denotes ‘A’ specification Denotes a comment line .Comments may be entered between positions 8 and 80. This position is not used for logical files and must be blank Record format name Join Specification Field name Key field Name Select Criteria Omit Criteria This position is not used for logical files and must be blank Record name or field name or key field name Denotes that a definition and attributes of the named filed are to be referenced from a previously defined field. Length of the field the following are the valid lengths for various types of fields. Character 1 to 32766 Hexadecimal 1 to 32776 Binary 1 to 9 Numeric 1 to 31 Packed decimal Zoned decimal Binary Floating point Character Hexadecimal Date Time 36 of 148

Positions

Name

Entry T Z

36-37 38

Decimal Position Usage

‘B’

39-44

Location

Blank

45-80

Keywords

Explanation Timestamp Number of decimal positions. Both input and output Default to B Thos column is reserved and is not used by logical files.

Logical file Keywords Keywords used in logical files are divided into four parts, namely , File level keywords Record level keywords Field level keywords Key-field keywords There are in all over 45 keywords associated with logical files .These keywords are used to provide further qualification to the file , record format, field or key fields. Some of the more commonly used keywords are explained in the subsequent section. File Level Keywords  DYNSLT Dynamic Select Used to instruct that selection of records according to the criteria specified in the file must be maintained dynamically as and when records are written into or retrieved from the database file that is pointed to by the logical file.  FCFO First Changed First out When duplicate key exists in a file this keyword is used to specify that the record that was changed earliest is to be retrieved.  FIFO First In First Out When duplicate key exists in a file this keyword is used to specify that the record that was written earliest is to be retrieved.  LIFO Last In First Out When duplicate key exists in a file this keyword is used to specify that the record that was written most recently is to be retrieved.  UNIQUE Unique Key Use to indicate that records with duplicate key value will not allowed in this file.

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Record Level Keywords  PFILE Physical File Used to name the physical file that is being pointed to by the named logical file .This keyword is mandatory for every logical file definition.  TEXT Text Used to assign descriptive text for the record format. Field Level Keywords  ALIAS Alias Name Used to indicate the alias name for the named field .  CHECK Check Values Used to provide certain validity for the named field. The value associated with this keyword are as follows: AB Allow Blanks ME Mandatory Entry MF Mandatory Full M10 Modulus 10 Validation M10F Modulus 10 Validation(IBM variation) M11 Modulus 11 Validation M11F Modulus 11 Validation(IBM variation) Example,CHECK (ME).  CMP/COMP Compare Value Used to provide validation to specify that named field must contain value specified in this parameter.Example,COMP(*EQ’A’)  COHDG Column Heading Used to provide descriptive text about the named field.This text is used when the field is used in a certain application development tools such as Data File Utility(DFU)and QUERY.Upto three strings of 20 characters each can be specified .  DATFMT Date Format Used to define the format (namely one of either ,YY/MM/DD or MM/DD/YY or DD/MM/YY)in which date is to be stored in the named field.  DATSEP Date Separator Used to identify the character used to separate the elements of a date.  EDTCDE Edit Code Used to identify a system-supplied editing rule for the named field.Rules could include zero suppression,zero balance ,sign,etc.  TEXT Text Used to assign descriptive text to the named filed to be used in all future references of the named filed.Example ,TEXT(‘Customer Code’).  TIMFMT Time Format Used to define the format in which time is to be stored in the named field.  TIMSEP Time Separator Used to identify the character to be used to separate the elements namely hour,minute and second of time. 38 of 148

 VALUES Values Used to assign one or more values that are allowed as valid input into the named field. Example,VALUES(‘A’’B’’C’”D’’E’). Key Field Level Keywords  ABSVAL Absolute Value Used to indicate that when retrieving records from the named file the sign of the key-field is to be ignored and only the absolute value of the field is to be used for purpose of ordering sequences.  ALL All Used in conjunction with Select and Omit criteria specification to indicate that all records not fulfilling the Select or Omit criteria must be selected or omitted as the case may be.  DESCEND Descending Sequence Used to specify an ordering sequence for the retrieval of records from the named file.When retrieving records from the named file,the records would be sequenced in descending order of the named key-field.  SIGNED Signed Used to specify that the sign of the named key-field is to be considered for purposes of ordering sequence when retrieving records from the named file.  UNSIGNED Unsigned Used to specify that the sign of the named key-field is to be ignored for purposes of ordering sequence when retrieving records from the named file. Join Logical Files  A join logical is a logical file which contains definitions required to join two or more different files based on certain user-defined join conditions.  The first file being joinng is called the ‘Primary file’ while the other are called ‘Secondary files’.The primary file and atleast one of the secondary files must be a physical file.  When accessing a join file record, the system internally reads a record from the primary file and picks up the corresponding record from the secondary file based on the userdefined join criteria and then presents the combined data to the accessing program in one consolidated record.  If required, when specifying the primary file and secondary file ,only certain fields from either file may be selected for join file record format rather than all the fields from both the files. But all the fields indicated in join criteria must be selected .  Special consideration * You cannot change a physical file using a join logical file. * You can specify only one record format in join logical file. * Commitment control cannot be used with join logical files.

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Join Level Keywords The keywords used in join logical files are:  JFILE Join File Identifies the names of the two files being joined.This keyword is specified at the record level.  JFLD Join Field Used to name the fields that are to be used for purposes of joining the primary file and secondary file.Join fileds must have the same attributes.This keyword is specified at the record level.  JOIN Join Identifies the names of the two files being joined.This keyword is specified at the join level.  JREF Join Reference File Identifies the file from which the named fields is to be retrieved from.This keyword is specified at the field –level.

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Examples of database files in DDS: Example of a field reference file: This example defines all of the fields used in an application and refers to fields only within the field reference file itself. The following keywords are important in the example: COLHDG EDTCDE(Z) REFFLD REFSHIFT TEXT The following field reference file (MLGREFP) describes all fields used by any program in the application. The other files use the fields in this file. Figure 1. DDS for a Field Reference File 00010A** FLDREF MLGREFP 00020A (1)R MLGREFR 00030A ACTNUM 00040A 00050A ACTTYP 00060A 00070A 00080A NAME 00090A 00100A ADDR 00110A 00120A CITY 00130A 00140A STATE 00150A ZIP 00160A 00170A BATNUM 00180A 00190A TRNTYP 00200A 00210A 00220A XACTNM 00230A XACTTTP 00240A XNAME 00250A XADDR 00260A XCITY 00270A XSTATE 00280A XZIP 00290A TRNNUM 00300A 00310A MLGLK1 00320A 00330A

MAILING LIST FIELD REFERENCE FILE TEXT('Mailing List Field Reference') 5 0 COLHDG('Account' 'Number') EDTCDE(Z) 1 0 COLHDG('Acct' 'Type') TEXT('Acct Type 1=Bus 2=Gvt + 3=Org 4=Sch 5=Pvt 9=Oth') 18 COLHDG('Name') REFSHIFT(X)(4) R (2) (2)REFFLD(NAME) COLHDG('Address')(3) R (2) (2)REFFLD(NAME) COLHDG('City') (3) 2 COLHDG('State') 5 0 COLHDG('ZIP' 'Code') EDTCDE(X) 6 0 COLHDG('Batch' 'Number') EDTCDE(Z) 1 COLHDG('Trans' 'Type') TEXT('Trans Type A=Add + C=Change D=Delete') R REFFLD(ACTNUM) R REFFLD(ACTTYP) R REFFLD(NAME) R REFFLD(ADDR) R REFFLD(CITY) R REFFLD(STATE) R REFFLD(ZIP) 5 0 COLHDG('Transaction' 'Number') EDTCDE(Z) 3 0 COLHDG('Lock' 'Control') TEXT('Control Number Used for + record locking')

Legend:

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(1) Like all physical files, a field reference file has only one record format. The R in position 17 specifies that MLGREFR is the record format name. (2) The Rs in position 29 and REFFLD in positions 45 through 80 specify that the fields ADDR and CITY are to have the same attributes as NAME. (3) Specifying COLHDG for ADDR and CITY overrides the COLHDG attribute for NAME, which otherwise would have been in effect. (4) Specifying REFSHIFT for NAME will cause the keyboard shift specified (X) to be used when this field (NAME) is referred to in a display file.

Example of a physical file with a new record format: The REF keyword is important in the following example. This file has one record format. The names of all fields in the record format are specified. This example uses fields in a reference file (REF keyword) and uses a keyed-sequence access path. The following physical file (called CUSMSTP for customer master physical file) describes the fields physically present in the database. Figure 2. DDS for a Physical File 00010A* 00020A* SAMPLE PHYSICAL FILE(CUSMSTP) 00030A* 00040A 00050A (2) R CUSMST 00060A ACTNUM R (3) 00070A NAME R (3) 00080A ADDR R (3) 00090A CITY R (3) 00100A STATE R (3) 00110A ZIP R (3) 00120A (4) SEARCH 10 0 00130A (4) CRDLMT 8 2 00140A (5) K ACTNUM

(1) REF(MLGREFP) TEXT('Customer Master Record')

Legend: (1) At the file level, the REF keyword refers the OS/400 program to the physical file MLGREFP, which is a field reference file for this database. (2) At the record level, R in position 17 specifies that CUSMST is the record format name of the record in this file. (There can only be one record format in a physical file.) (3) At the field level, Rs in position 29 specify that the attributes of fields of the same name in the REF file are to be used as attributes of these fields. (4) The fields SEARCH and CRDLMT are not defined in MLGREFP; therefore, their field attributes are specified here. (5) At the key field level, K in position 17 specifies that ACTNUM is the key field for the file.

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Example of a logical file specifying multiple formats and new keys: The PFILE keyword is important in the following example. The example uses new field specifications and provides two record formats. Each record format provides a different view of the associated physical file and uses a key different from the associated physical file. Figure 3. DDS for a Logical File Specifying New Keys 00010A* 00020A* SAMPLE LOGICAL FILE 00030A 00040A R CUSMST1 00050A ACTNUM 00060A NAME 00070A STATE 00080A LASTNAME 00090A (2) K ACTNUM 00100A* 00110A R CUSMST2 00120A ACTNUM 00130A NAME 00140A ZIP 00150A K *NONE 00160A (2) K NAME

(1)PFILE(CUSMSTP)

I

(3)SST(NAME 8 10) (1)PFILE(CUSMSTP)

Legend: (1) The two record formats (CUSMST1 and CUSMST2) in this logical file are based on the same physical file (CUSMSTP). (2) Record format CUSMST1 has a key different from record format CUSMST2, providing the application program with a different sequence of the same records. (3) The LASTNAME field is a substring of the field NAME. The usage I in position 38 must be specified since this is not a join logical file.

Example of a logical file specifying a new record format: The UNIQUE keyword is important in the following example. The example specifies a record format different from the associated physical file. The following logical file (called CUSMSTL2 for customer master logical file two) uses some of the fields in the physical file CUSMSTP. Another logical file could name all fields, name fields in other physical files as well, concatenate fields, change the order of fields, rename fields, or choose different key fields. In this logical file, the programmer merely omitted some fields from the physical file.

Figure 4. DDS for a Logical File 00010A*

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00020A* SAMPLE LOGICAL FILE (CUSMSTL2) 00030A* 00040A 00050A R CUSREC 00060A 00070A ACTNUM (3) 00080A NAME (3) 00090A ADDR (3) 00100A (4)K ACTNUM

(1)UNIQUE (2)PFILE(CUSMSTP) TEXT('Logical File Master Record')

Legend: (1) The UNIQUE keyword specifies that records with duplicate keys are not allowed within a member of this logical file. (2) The keyword PFILE (required for logical files) specifies CUSMSTP. (3) The field names do not have R specified in position 29 as they would in physical files or in any device file. (4) As in CUSMSTP, the field ACTNUM is treated as a key field.

Example of a join logical file: The following join logical file joins three physical files (PF1, PF2, and PF3) so that an application program can get name, address, and salary information in one input operation, even though the information is stored in three different physical files. The following keywords are important in the example: • • • •

JFILE JFLD JOIN JREF

Figure 5. DDS for a Join Logical File 00010A 00020A 00030A 00040A 00050A 00060A 00070A 00080A 00090A A

(1)R JOINREC J (3) J (4) (4) (4) (4)

NAME ADDR PHONE SALARY

(2) JFILE(PF1 PF2 PF3) JOIN(PF1 PF2) JFLD(NAME NAME) JOIN(PF2 PF3) JFLD(NAME NAME) (5) JREF(1)

Legend: (1) R identifies the record format. There can be only one record format in a join logical file. (2) The JFILE keyword specifies that PF1, PF2, and PF3 are the physical files on which this join logical file is based. Because it is specified first, PF1 is the primary file. There are two secondary files: PF2 and PF3. (3) J identifies the join specifications. With two secondary files in this join logical file, there must be two join specifications. Each join specification defines how a pair of files is to be joined, 44 of 148

as follows: JOIN is required when more than two physical files are being joined, and it identifies which two files are being joined in this join specification. In the first join specification, PF1 and PF2 are joined. In the second join specification, PF2 and PF3 are joined. Note: Secondary files can be joined to either the primary file or to another secondary file. In this example, PF2 in the second JOIN keyword could be PF1; there would be no difference in the order of records supplied to the program or in performance. JFLD identifies which fields are used to link together records from the physical files being joined. In the first join specification, NAME from PF1 links with NAME from PF2. In the second join specification, NAME from PF2 links with NAME from PF3. •

(4) The field names show which fields are presented to the program. At least one field name is required. (5) The JREF keyword identifies which physical file to search for the field name; in this example, NAME from PF1 is used. Note the use of the direct file number: JREF(1) indicates to use the first file on the JFILE keyword, which is PF1.

DDM Files The DDM files is used as a reference file by AS/400 program to access files located on any target system in the AS/400 network. DDM files may be created through two methods, either by the work with DDM files (WRKDDMF) command, then form the list display press F6 to create a DDM file or by the Create DDM file (CRTDDMF) command directly on the source system. Additional Recommended Reading Material 1. SC41-9659-02 AS/400 : Database Guide 2. SC41-9620-02 AS/400:DDS Reference

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Chapter V: SDA and Display Files

Screen Design Aid(SDA): This is a development tool is to aid in the creation of user interfaces on the AS/400.This tool allows a programmer to "paint" screens and menus used by a program from within a simple editor, defining input and output fields and special text attributes. These screens may then be called from an application program, allowing the program to have all the features of the AS/400 user interface without direct programming of the appearance of the interface. SDA can be invoked by either selecting option ‘9’ from Programmer’s menu or through typing the command ‘STRSDA’ from AS/400 command entry line. AS/400 Screen Design Aid (SDA) Select one of the following: 1. Design screens 2. Design menus 3. Test display files

Selection or command ===> F1=Help F3=Exit F4=Prompt F9=Retrieve F12=Cancel (C) COPYRIGHT IBM CORP. 1981, 2000.

 Screen Designing: The following function keys can be used while designing your image: 

F3=Exit 46 of 148

Terminates screen design session.The Exit Design Image work screen displays appears where there is a choice to save the work , and return to the Work with Display records menu.  F4=Prompt Shows Work with Fields display.  F6=Condition Shows the Condition Work Screen display.  F9=Select additional records Selects additional records to display on the Design image work screen.  F10=Database Shows the display for selecting Database Files display.  F11=Non-display selected fields Toggle between two fields lists that are displayed on the bottom row of the work screen.  F12=Cancel Save the current work and return to the Work with Display records display. (Note:Anything that have been typed since last pressed enter is not processed.)  F14=Ruler Place a vertical and horizontal ruler on the Design Image work screen to position the cursor.The ruler does not interfere with the data.Press F14 to remove the ruler .Defining fields on the ruler may cause results that cannot be predicted.  F15=Subfile Prompt. This function will work only when a subfile exists.Press F15 display prompt on the bottome row of the Design Image work screen that allows changing the subfile line(SFLLIN) and subfile page(SFLPAG) sizes that were in effect for the current record being defined.  F17=Print Print the current contents of the Design Image work screen.  F18=Tab Moves the cursor to the attribute position of the next field.  F19=Back Tab Moves the cursor to the attribute position of the previous field.  F20=Reverse Image Constants Switch the reverse imaging of constants on and off.This reverse imaging is temporary and does not affect the compiled image.

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Use F20 to determine the starting and ending points of the constants. Constants which have the underline attribute (but not the reverse image and highlight attributes) will not be displayed in reverse image. Constants that are not currently displayed will be highlighted and will appear in reverse image. F21=Display additional records.



Displays the additional records with the primary record. Press F21 again to display only the primary record. Use this function key to determine which fields on the display belong to the primary record. Only the fields of the primary record can be changed.

Adding fields. To add a user defined field, type + followed by I (input), O(output), or B(both) for alphabetic fields, or followed by 3(input), 6(output), or 9(both) for numeric fields and press Enter. To add a floating point field, add a numeric field followed by E (single-precision) or D(double-precision) and press Enter. Indicate the length of a field by the number of characters following +, or by the length specified in brackets after the first characters. Adding constants To add a new constant or change an existing constant 1. Type a constant. A blank character ends the constant. 2. Type constants with single quotation marks to define separate constants for each character string(word) that is followed by a blank. 3. Surround a character string with single quotation marks to define single constant. 4. Surround several constants with single quotation marks to redefine them as one constant. 5. Use a double quotation mark to end one constant and start a new constant while taking up only one position. Adding fields from a database file The fields selected from the database file appear on the bottom row of the Design Image work screen. Move fields from the bottom line to your display by typing & followed by the field number, in multiple mode, and the column heading position and pressing Enter. he fields begin in the position where you type &.

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Moving, Copying and Shifting fields Reposition fields on the screen by using their attribute position. (Note: The attribute position is the space directly in front of the field. Press F19 to go to the attribute position of the previous field. Press F18 to go to the attribute position of the next field.) Choose from the from the following methods and press Enter. 

Centering a field

Type AC in the attribute position of the field to move the field to the center of the same row. 

Moving a field - , =

Type – in the attribute position of the field and type = where you want the field to appear. 

Copying a field - , ==

Type – in the attribute position of the field and type == where you want a copy of the field to appear.  Moving a block of fields -, -, = Type – in the upper left corner of the block of fields. Type – in the lower right corner of the block of fields so the – is one character beyond the longest field in the block. Type = where you want the group of fields to appear.  Copying a block of fields -, - ,== Type – in the upper left corner of the block of fields. Type – in the lower right corner of the block of fields so the – is one character beyond the longest field in the block. Type == where you want the group of fields to appear.  Shifting a field Type > after the field (over the ending attribute byte), to shift the field left or right as far as the signs extend. You may type any number of > or