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From:Song Ken Vern-E11804 Date:June 23 2006 3:33am
Subject:RE: if else statement
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Hi Peter,

>SELECT IF(col1=3, (Select col2 from table2 where table2.id = 1), (Select
>col2 from table3 where table3.id = 1)) FROM table1 WHERE id=1;

Thanks you for you answers.

Can I put SELECT statements inside the IF statement?
Mysql give error 
ERROR 1064: Error in SQL syntax.

Under Control Flow functions of the manual, it says 
IF(expr1,expr2,expr3)
    If expr1 is TRUE (expr1 <> 0 and expr1 <> NULL) then IF() returns expr2,
else it returns expr3. IF() returns a numeric or string value, depending on the context
in which it is used.

But doesn't say what expr is. Examples only show numeric and string functions.

-----Original Message-----
From: Peter Lauri [mailto:lists@stripped] 
Sent: Wednesday, June 21, 2006 4:43 PM
To: zodin@stripped; Song Ken Vern-E11804
Cc: mysql@stripped
Subject: RE: if else statement

SELECT IF(col1=3, (Select col2 from table2 where table2.id = 1), (Select
col2 from table3 where table3.id = 1)) FROM table1 WHERE id=1;

That should do it.

-----Original Message-----
From: Thomas Lundström [mailto:zodin@stripped]
Sent: Wednesday, June 21, 2006 7:51 PM
To: Song Ken Vern-E11804
Cc: mysql@stripped
Subject: Re: if else statement

Not sure what you're aming for here and how your data is structured but why not use a join
and alias and fetch all info in one select and then solve what you need in your code?

Something in the line of:

select t2.col2 from_t2, t3.col2 from_t3 from table1 t1, table2 t2, table3 t3 where t1.id =
t2.id
  and t1.id = t3.id
  and t1.id = 3

Maybe you can do something like that?

Regards,

Thomas L.


ons 2006-06-21 klockan 17:16 +0800 skrev Song Ken Vern-E11804:
> 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?
> 
> Thanks
> 
> --
> Ken
> e11804
> 



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Thread
if else statementSong Ken Vern-E1180421 Jun
  • Re: if else statementJørn Dahl-Stamnes21 Jun
  • Re: if else statementThomas Lundström21 Jun
    • RE: if else statementPeter Lauri21 Jun
RE: if else statementSong Ken Vern-E1180423 Jun
  • Re: if else statementMichael Stassen23 Jun
    • Re: if else statementThomas Lundström25 Jun