Published on March 10, 2014
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
DR.GIRIJA NARASIMHAN 2
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
relational algebra projection, selection, database, ... rel algebra projection ... by Dr. Girija Narasimhan 174 views.
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