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How many rows will be there in the output of the following query?

asked in Databases by Active (2.3k points)   | 41 views

1 Answer

+1 vote
The second query always returns 0.

Thus, the table returned by second query consists of 1 tuple.

 

Now, exists( table containing single tuple)= true for every employee of 1st relation.

 

Thus, bove query will return all the tuples of the 1st relation.
answered by Veteran (14.7k points)  

So it means that whenever we have an internal query consisting of count() then in case of exists we will always get all tuples because count always return an integer  value.

plz varify?

Yes, I suppose that count() will always return an integer. But, today I will execute the query and let you know the actual outcome.
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