rel algebra selection girija
DESCRIPTION
set theory, selection, relational algebra, database - all the exercise sildes i have downloaded or referred from websites. i just orgainsed as topicwise for readers, www.youtube.com - video is available (search as "dr.girija narasimhan")TRANSCRIPT
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.
selection
milk milk_type price Al-marai Full_Fat 2.50 Al-marai Refresh 2.75 Lancor Full_Fat 2.50 Lancor Refresh 3.00
Prices := σ milk=‘Al-marai’(Sells):
milk milk_type Al-marai Full_Fat Al-marai Refresh
Sells
price 2.50 2.75
Display only the milk Al-marai
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For example, the operation SID=101 selects all tuples in the input relation which have the value 101 in column SID.
Exercise 1- selection Exercise 2- selection
Select only A which has value one
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For example, the operation SID=101 selects all tuples in the input relation which have the value 101 in column SID.
Selection – exercise 1 & 2 Result
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Selection – exercise 3
Select the employee whose age is less than 30 or salary is greater than 4000
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Selection – exercise 3 solution
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Selection – exercise 4
Select where placeofbirth and residence place have same value or same place.
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Selection – exercise 4 solution
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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
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Selection – exercise 5 solution
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Selection – exercise 6
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Selection – exercise 6 solution
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Selection – exercise 7
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Selection – exercise 8
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Selection – exercise 8 solution
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