On Wednesday 21 June 2006 11:16, Song Ken Vern-E11804 wrote:
> Hi,
>
> I'm trying to build a query in using SQL instead of doing it in Perl.
>
> I am trying to do something like this :
>
> If ((select col1 from table1 where id = 1) == 3)
> Then
> Select col2 from table2 where table2.id = 1;
> Else
> Select col2 from table3 where table3.id = 1;
>
> In Perl I would probably do have to access the DB twice.
>
> Select col2 from table1 where if = 1;
>
> If (col2 == 3) {
> Select col2 from table2 where table2.id = 1;
> } else {
> Select col2 from table3 where table3.id = 1;
> }
>
> I've read the manual on subqueries but the example don't indicate how I
> can
> do a conditional test using a subquery?
>
> Am I on the right track or is there another way to do this?
Maybe:
(SELECT col2 FROM table2 left join table1 on table1.id=1 where table1.col1=3
and table2.id=1)
UNION
(SELECT col2 FROM table3 left join table1 on table1.id=1 where table1.col1<>3
and table3.id=1);
I have not tested it...
--
Jørn Dahl-Stamnes
homepage: http://www.dahl-stamnes.net/dahls/
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