E No |
Ename |
DeptNo |
---|
E001 |
A |
10 |
E002 |
B |
10 |
E003 |
B |
5 |
E004 |
C |
10 |
E005 |
D |
20 |
E001 |
A |
20 |
E003 |
B |
10 |
So , if I do the first query
it will give
Union
so, Union will remove duplicate entries.(i,e E002)
ENo |
E005 |
E002 |
E001 |
E004 |
E003 |
But if we do the second query , we will get the duplicate tuples.
So, option (b) is true , Q1 is subset of Q2