How to replace OR operator with UNION operator?

Question

Here is my query:

SELECT 
    h.id,
    h.subject,
    h.body matnF,
    h.amount,
    h.keywords tags,
    h.closed,
    h.author_id author,
    h.AcceptedAnswe         


        

Answer 1

The first thing I would try is a subquery:

from ((select q.* from quanda q where q.id = :id1) union
      (select q.* from quanda q where q.related = :id2)
     ) left join
     . . .

Note: This really wants indexes on quanda(id) and quanda(related) for performance.

If few rows are selected, then this might be much faster.