Re: Delete and select in the same query

[Peter Brawley]

Yes, sorry, that's the select cmd ...

select id_comment from comments where user_id=N
union
select id_comment from comments a
join comments b on a.id_parent=b.id_comment
where b.user_id=N;

The simplest way to delete those rows is probably to run these two deletion commands ..

delete from comments where user_id=N

delete a
from comments a join comments b on a.id_parent=b.id_comment
where b.user_id=N;

> why you use union?

Union does exclusive or on statement results (union all does inclusive or). It can be simpler & more efficient to do the ORing at statement level rather than in the Where clause.