Question

In a case where I have to perform 2 queries, I wanted to replace it by simply one single line of query. Example:

select col1, col2 from tableA where col3 = 'a';

This will return (consider) 2 rows:

col1    col2

abc     abc.bcd
xyz     xyz.pqr

Now, in a second table we made a different query for each rows from query 1:

   select col1 from tableB where col2 = 'abc';
   (AND)
   select col1 from tableB where col2 = 'xyz';

This will give a result set like:

 TableB
 col1    
 1111    
 2222   

If the question is unclear kindly mention I shall try to elaborate with better example.

(although database vendor is not issue, I am comfortable with oracle or mysql. Thanks).

Answer 1

Try this:

select col1 
from tableB
where col2 in (select col1 
               from tableA 
               where col3='a')