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SQL

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1 1 vote
Q1: (Select eno from emp where deptno=10) union(Select eno from emp where deptno=20)

Q2:(Select eno from emp where deptno=10 or deptno=20)

Which one is true?

1)Q1⊆Q2

2)Q2⊆Q1

3)Q1=Q2

4)data inefficient

1 Answer

Best answer
3 3 votes
1.should be ans..

Since" union" eliminates the duplicates by default behavior since it is set operation.

In SQL "select " doesn't eliminate duplicates.
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