Rel algebra selection girija

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Information about Rel algebra selection girija

Published on March 10, 2014

Author: nbgirija



set theory, selection, relational algebra, database - all the exercise sildes i have downloaded or referred from websites. i just orgainsed as topicwise for readers

selection R1 := σC (R2)  C is a condition (as in “if” statements) that refers to attributes of R2.  R1 is all those tuples of R2 that satisfy C. Sells milk Al-marai Al-marai Lancor Lancor Display only the milk Al-marai Prices := milk_type Full_Fat Refresh Full_Fat Refresh price 2.50 2.75 2.50 3.00 σ milk=‘Al-marai’(Sells): milk Al-marai Al-marai DR.GIRIJA NARASIMHAN milk_type Full_Fat Refresh price 2.50 2.75 1


Exercise 1- selection For example, the operation SID=101 selects all tuples in the input relation which have the value 101 in column SID. DR.GIRIJA NARASIMHAN Exercise 2- selection Select only A which has value one 3

Selection – exercise 1 & 2 Result For example, the operation SID=101 selects all tuples in the input relation which have the value 101 in column SID. DR.GIRIJA NARASIMHAN 4

Selection – exercise 3 Select the employee whose age is less than 30 or salary is greater than 4000 DR.GIRIJA NARASIMHAN 5

Selection – exercise 3 solution DR.GIRIJA NARASIMHAN 6

Selection – exercise 4 Select where placeofbirth and residence place have same value or same place. DR.GIRIJA NARASIMHAN 7

Selection – exercise 4 solution DR.GIRIJA NARASIMHAN 8

Selection – exercise 5 Select where person whose age is greater than or equal to 34 Select the person whose age and weight should be same DR.GIRIJA NARASIMHAN 9

Selection – exercise 5 solution DR.GIRIJA NARASIMHAN 10

Selection – exercise 6 DR.GIRIJA NARASIMHAN 11

Selection – exercise 6 solution DR.GIRIJA NARASIMHAN 12

Selection – exercise 7 DR.GIRIJA NARASIMHAN 13

Selection – exercise 8 DR.GIRIJA NARASIMHAN 14

Selection – exercise 8 solution DR.GIRIJA NARASIMHAN 15

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