Question

I have a query like this:

SELECT t1.id,     (SELECT COUNT(t2.id)      FROM t2      WHERE t2.id = t1.id           ) as num_things FROM t1 WHERE num_things = 5; 

The goal is to get the id of all the elements that appear 5 times in the other table. However, I get this error:

ERROR: column 'num_things' does not exist SQL state: 42703 

I’m probably doing something silly here, as I’m somewhat new to databases. Is there a way to fix this query so I can access num_things? Or, if not, is there any other way of achieving this result?

Answer 1

I think you could just rewrite your query like so:

SELECT t1.id FROM t1 WHERE (SELECT COUNT(t2.id)      FROM t2      WHERE t2.id = t1.id           ) = 5;