Select Operation (s) in Python
The Select operation selects tuples that satisfy a given predicate.
Let’s understand this operation with few examples:
Consider the following relation (R1) :
R1 : FACULTY-1
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FNo FName DNo Qual Salary
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22 Riya 21 Ph.D. 55000
24 Priya 22 MTech 50000
25 Zayn 22 MTech 42000
27 Harry 23 MTech 28000
30 Sia 23 MTech 32000
33 Max 24 Ph.D. 53000
35 Fred 24 Ph.D. 52000
37 Diva 25 MTech 26000
39 Ben 25 MTech 24000
40 Trent 25 MTech 34000
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Example-1 : Find the tuples belonging to DNo 24.
Sol: sDNo = 24 (Faculty-1)
Output :
FNo FName DNo Qual Salary
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33 Max 24 Ph.D. 53000
35 Fred 24 Ph.D. 52000
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Example-2 : Find the tuples having Qual : Ph.D.
Sol: s qual = ‘Ph.D.’ (Faculty-1)
Output :
FNo FName DNo Qual Salary
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22 Riya 21 Ph.D. 55000
33 Max 24 Ph.D. 53000
35 Fred 24 Ph.D. 52000
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Example-3 : Find the tuples having Qual : MTech and drawing at least 30,000.
Sol: squal = ‘MTech.’ ˄ Salary > 30000 (Faculty-1)
Output :
FNo FName DNo Qual Salary
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25 Zayn 22 MTech 42000
30 Sia 23 MTech 32000
40 Trent 25 MTech 34000
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