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Multiple Joins

Author

Topic

jcb267
Constraint Violating Yak Guru

291 Posts

Posted - 2011-01-10 : 12:32:26

Hi -

I need data from 3 different tables, I am making multiple joins between the tables. This is what I have thus far, it is running but seems to be very inefficient.

dw.dbo.PremiumBilling pb inner join dw.dbo.sponsordemographics sd on pb.sponsorid = sd.sponsorid, dw.dbo.PremiumBilling pb2 inner join dw.dbo.sponsorpolicy sp on pb2.policynumber = sp.policynumber

Is this even correct? What can I do to speed it up??

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2011-01-10 : 12:42:21

its not correct as it has a cross join in between. probably you meant this?


...
dw.dbo.PremiumBilling pb 
inner join dw.dbo.sponsordemographics sd 
on pb.sponsorid = sd.sponsorid
inner join dw.dbo.sponsorpolicy sp 
on pb.policynumber = sp.policynumber

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

jcb267
Constraint Violating Yak Guru

291 Posts

Posted - 2011-01-10 : 12:48:17

Yes, that is what I meant. Thanks!!

quote:
Originally posted by visakh16

its not correct as it has a cross join in between. probably you meant this?

...
dw.dbo.PremiumBilling pb
inner join dw.dbo.sponsordemographics sd
on pb.sponsorid = sd.sponsorid
inner join dw.dbo.sponsorpolicy sp
on pb.policynumber = sp.policynumber

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

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2011-01-10 : 12:50:21

welcome

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

jcb267
Constraint Violating Yak Guru

291 Posts

Posted - 2011-01-10 : 12:51:42

what is a cross join?

quote:
Originally posted by visakh16

its not correct as it has a cross join in between. probably you meant this?

...
dw.dbo.PremiumBilling pb
inner join dw.dbo.sponsordemographics sd
on pb.sponsorid = sd.sponsorid
inner join dw.dbo.sponsorpolicy sp
on pb.policynumber = sp.policynumber

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

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2011-01-10 : 13:03:03

cross join is equivalent to cartesian product. ie it returns all possible combinations of resultset from two queries

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

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