Question

This is likely very easy, I haven’t used sql in a while and have run into this problem. Basically, as part of a larger statement I only want to return a row from a select statement if a count from an inner select statement is equal to 3. How do I do that?

For example…

select rev.name, s.title 
from reviewer rev, song s, rating r 
where (r.rID = rev.rID) and (r.mID = s.sID) and ...[rest goes here];

Where the ‘rest’ is that I only want to return when reviewer rev has reviewed song s twice, and r.value was larger the first time (we denote first time as the one with the oldest r.date_of_rating.

This is clearly a count and compare, but I don’t know how to lay it out in proper SQL syntax. Any help would be greatly appreciated. Thanks

Answer 1

I’m not sure your example gives enough info.

But it sounds like you need a ‘HAVING’ clause.

e.g.

SELECT rev.name, s.title, count(r.mId)
FROM reviewer rev, song s, rating r 
WHERE (r.rID = rev.rID) AND (r.mID = s.sID) 
GROUP BY rev.name, s.title
HAVING count(r.mId) = 3