"Jaime Casanova" <el_vigia_ec(at)hotmail(dot)com> writes:
> AND
> CPA.cur_paralelo = ALL (SELECT cur_paralelo FROM aca_t_curso ...)
Wait a second ... we are all overthinking the problem. The subselect
returns three *different* values. It is not possible for any
CPA.cur_paralelo values to be simultaneously equal to all three.
So this test certainly fails at every row of CPA.
Perhaps you meant "= ANY"?
regards, tom lane