ERD Examples

The (min,max) notation (0,1)

(1,1)

(1,1)

(1,N)

SUMMARY OF ER-DIAGRAM NOTATION FOR ER SCHEMAS S&$'

Meaning ENTITY TYPE WEAK ENTITY TYPE RELATIONSHIP TYPE IDENTIFYING RELATIONSHIP TYPE ATTRIBUTE KEY ATTRIBUTE MULTIALUED ATTRIBUTE !OMPOSITE ATTRIBUTE DERIED ATTRIBUTE

E1 E1

E"

R  R  R 

 N ($in,$a%)

E" E

TOTAL PARTI!IPATION OF E" IN R  !ARDINALITY RATIO 1#N FOR E 1#E" IN R  STRU!TURAL !ONSTRAINT ($in, $a%) ON PARTI!IPATION OF E IN R 

ER DIAGRAM – Entity Types are: EMPLOYEE DEPARTMENT PRO!ECT DEPENDENT

!OMPANY ER S*+e$a Diaga$  -.ing ($in, $a%) n/a/in

De.igning an ER Diaga$ !n.ie /+e 2ing .e/  e3-ie$en/.  a Uni4e.i/& a/a'a.e5 De.ign an ER iaga$  /+i. a66i*a/in# 7

7 7 7

7

T+e -ni4e.i/& 8ee6. /a*8  ea*+ ./-en/9. na$e, ./-en/ n-$'e, .*ia .e*-i/& n-$'e, *-en/ ae.. an 6+ne n-$'e, 6e$anen/ ae.. an 6+ne n-$'e,  'i/+a/e, .e%, *a.. (e.+$an, ga-a/e), $a: e6a/$en/, $in e6a/$en/ (i an&), egee 6ga$ (B5A5, B5S5, 555 P+5D5)5 S$e -.e a66i*a/in. nee / ee / /+e *i/&, ./a/e, an ;i6 *e  /+e ./-en/9. 6e$anen/ ae.. an / /+e ./-en/9. a./ na$e5 B/+ .*ia .e*-i/& n-$'e an ./-en/ n-$'e ae -ni3-e  ea*+ ./-en/5 A ./-en/. 2i +a4e a/ ea./ a $a: e6a/$en/5 Ea*+ e6a/$en/ i. e.*i'e '& a na$e, e6a/$en/ *e, i*e n-$'e, i*e 6+ne, an *ege5 B/+ /+e na$e an *e +a4e -ni3-e 4a-e.  ea*+ e6a/$en/5 Ea*+ *-.e +a. a *-.e na$e, e.*i6/in, *-.e n-$'e, n-$'e  *ei/., e4e an eing e6a/$en/5 T+e *-.e n-$'e i. -ni3-e  ea*+ *-.e5 Ea*+ .e*/in +a. an in./-*/, .e$e./e, &ea, *-.e, an .e*/in n-$'e5 T+e .e*/in n-$'e i./ing-i.+e. .e*/in.  /+e .a$e *-.e /+a/ ae /a-g+/ -ing /+e .a$e .e$e./e,  ?)  ea*+ ./-en/ an *a*-a/e. +i.  +e a4eage GPA5

Uni4e.i/& ER Diaga$ Degee  Na$e

S/-en/ID

Bi/+ a/e

SSN

DNa$e

Oi*eN-$'e 

Oi*eP+ne

De6a/$en/

S/-en/

Se%

D!e

Ma: In

!ege !a..

Min In

Ae.. !i/&

S/a/e

@i6

Oe 

!Na$e GaeRe6/ Le//e Gae

!-.eDe.* In./-*/

Yea  

!-.e !N-$'e 

GPA !ei/.

Se*/in

 N-$ei* Gae

Se*/inN-$'e

BengT

Se$e./e 

ER DIAGRAM FOR A "AN# DATA"ASE

 T+e Ben:a$in