Revision Notes Paper 3

Revision Notes Paper 3 Primary Key: It is an attribute or combination of attributes chosen to ensure that the records in a table are unique. The primary key is used to identify a record. Foreign Key: It is an attribute/or combination of attributes that links to or is the primary key in another table. Normalization 1st Normal Form A relation with repeating groups removed is said to be in First Normal Form (1NF). That is, a relation in which the intersection of each tuple and attribute (row and column) contains one and only one value. 2nd Normal Form A relation that is in 1NF and every non-primary key attribute is fully dependent on the primary key is in Second Normal Form (2NF). That is, all the incomplete dependencies have been removed. 3rd Normal Form A relation that is in 1NF and 2NF, and in which no non-primary key attribute is transitively dependent on the primary key is in 3NF. That is, all non-key elements are fully dependent on the primary key.

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the largest magnitude, positive number; 01111111/01111111 = 127/128x2^127 the smallest magnitude, positive number; 01000000/10000000 = 1/2x2^-128 (2^-129) the largest magnitude, negative number; 10000000/01111111 = -1x2^127 the smallest magnitude, negative number. 10111111/10000000 = -65/128x2^-128

Explain how accuracy can be improved in a floating point representation and state an effect it can have on the number represented. Increase the number of bits used for the mantissa by reducing the number of bits for the exponent The range of numbers is reduced because the size of the index of the power of two is reduced