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Where 0=1?

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Topic

yonabout
Posting Yak Master

112 Posts

Posted - 2010-10-07 : 05:16:21

I'm debugging an old stored procedure, and there's a section in it that goes something like this:

select a, b, c 
into #totals
from a
join b on a.a = b.a
where 0=1

what does the "Where 0 = 1" bit do?

I've also seen other selection criteria with "Where 1=1" after it.

I'm assuming that "Where 0 = 1" equates to false, and "Where 1=1" equates to true, but if that's right, what is true or false?

Cheers,

Yonabout

harsh_athalye
Master Smack Fu Yak Hacker

5581 Posts

Posted - 2010-10-07 : 05:19:04

It is a simple trick to create an empty temp table with same number of columns and format as in the select query.

Harsh Athalye
http://www.letsgeek.net/

Transact Charlie
Master Smack Fu Yak Hacker

3451 Posts

Posted - 2010-10-07 : 05:44:21

other tricks for the same things are SELECT TOP 0 x, y, z INTO foo FROM....

Charlie
===============================================================
Msg 3903, Level 16, State 1, Line 1736
The ROLLBACK TRANSACTION request has no corresponding BEGIN TRANSACTION

yonabout
Posting Yak Master

112 Posts

Posted - 2010-10-07 : 06:03:55

OK, Thanks.

Is "Where 1=1" used to do the same thing?

Cheers,

Yonabout

pk_bohra
Master Smack Fu Yak Hacker

1182 Posts

Posted - 2010-10-07 : 06:06:41

quote:
Originally posted by yonabout

OK, Thanks.

Is "Where 1=1" used to do the same thing?

Cheers,

Yonabout

Where 1 = 0 will create the other table with same structure (not index or pk) and the table will be empty

Where 1 = 1 will create the other table with same structure (not index or pk) and the table will also have data of base table.

Regards,
Bohra

I am here to learn from Masters and help new bees in learning.

yonabout
Posting Yak Master

112 Posts

Posted - 2010-10-07 : 06:27:40

Cool.

Thanks for your help

Cheers,

Yonabout

pk_bohra
Master Smack Fu Yak Hacker

1182 Posts

Posted - 2010-10-07 : 06:58:36