Example of relational operations, Database Management System

Assignment Help:

Consider the relation PERSON. If you want to display details of persons having age less than or equal to 30 than the select operation will be used as follows:

σ AGE <=30 (PERSON)

The resultant relation will be as shown:

PERSON_ID

NAME

AGE

ADDRESS

Sharad Gupta

Pocket 2, Mayur

Vihar.

Note:

1) Select operation is commutative; i.e.,

σ (σ (R)) = σ (σ (R))

Therefore, series of select can be applied in any order

2) More than one condition can be applied using Boolean operators OR & AND etc.

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