Query about using 0 = (select Count(*) in where

Please start any new threads on our new site at https://forums.sqlteam.com. We've got lots of great SQL Server experts to answer whatever question you can come up with.

All Forums

General SQL Server Forums

New to SQL Server Programming

Query about using 0 = (select Count(*) in where

Author

Topic

pinglu
Starting Member

2 Posts

Posted - 2012-05-27 : 14:46:01

Hi,

Can anyone help me understand the following SQL,

SELECT ID,OrchestrationName,LastRunDB,RunStatus,TRIGGERFLAG,ManualExtractEndDate from dbo.IH_CILASTRUN
where ProjectName = 'DynamicsSync' and OrchestrationName != 'DynamicsSync' and SkipRun != 1
AND 0 = (SELECT COUNT(*) from dbo.IH_CILASTRUN where ProjectName = 'DynamicsSync' and RunStatus = 'INPROCESS')

The thing that I don't understand is the "AND 0 = (SELECT COUNT(*) from dbo.IH_CILASTRUN where ProjectName = 'DynamicsSync' and RunStatus = 'INPROCESS')", I assume this is not a correlated query, but if it is not, then how do I interpret the result? Thanks in advance.

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2012-05-27 : 15:04:56

the way its written its not correlated to main query. what it does is it will cause query to return a resultset only if there are no rows satisfying conditions ProjectName = 'DynamicsSync' and RunStatus = 'INPROCESS' in the table dbo.IH_CILASTRUN

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

pinglu
Starting Member

2 Posts

Posted - 2012-05-27 : 15:24:04

Thanks for the reply, now I understand.

quote:
Originally posted by visakh16

the way its written its not correlated to main query. what it does is it will cause query to return a resultset only if there are no rows satisfying conditions ProjectName = 'DynamicsSync' and RunStatus = 'INPROCESS' in the table dbo.IH_CILASTRUN

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2012-05-27 : 15:45:38

no problem...you're welcome

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

SwePeso
Patron Saint of Lost Yaks

30421 Posts

Posted - 2012-05-27 : 18:29:14

SELECT ID,OrchestrationName,LastRunDB,RunStatus,TRIGGERFLAG,ManualExtractEndDate from dbo.IH_CILASTRUN
where ProjectName = 'DynamicsSync' and OrchestrationName != 'DynamicsSync' and SkipRun != 1
AND NOT EXISTS (SELECT * from dbo.IH_CILASTRUN where ProjectName = 'DynamicsSync' and RunStatus = 'INPROCESS')

N 56°04'39.26"
E 12°55'05.63"

Subscribe to SQLTeam.com

SQLTeam.com Articles via RSS

SQLTeam.com Weblog via RSS

- Advertisement -

Resources