Question

In SQL, can we always write an inner join statement as a main query and subquery?

For example,

 select * from gifts g where g.giftID in (select giftID from sentGifts);

can do a join and show the gifts sent in the sentGifts table, but it won’t be able to show the sentTime because that is inside the subquery?

Answer 1

No, you can only use that if the condition is a single value.

You can’t do that to a query like:

select *
from gifts g
inner join sentGifts s on s.giftType = g.giftType and s.giftDate = g.giftDate