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Join V/S Sub Query - which one is more Efficient

 
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Sasi Kiran Patha
Warnings : 2

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Joined: 19 Nov 2006
Posts: 73
Location: Hyederabad

PostPosted: Fri Jan 19, 2007 6:22 pm    Post subject: Join V/S Sub Query - which one is more Efficient
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Hi Guys,

I want to know among the JOIN and Sub Query in DB2 which one is more Efficient and which one uses the minimal no.of resources ...

Thanks,
Sasi Patha
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DavidatK

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Joined: 22 Nov 2005
Posts: 700
Location: Troy, Michigan USA

PostPosted: Fri Jan 19, 2007 11:45 pm    Post subject: Re: Join V/S Sub Query - which one is more Efficient
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Sasi,

Not enough information.

It really depend on how the JOIN or Sub query are implemented. Either could be better or not.

For a determination you would have to supply the SQL, Table definitions, and indexes
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Prajesh_v_p

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Joined: 24 May 2006
Posts: 133
Location: India

PostPosted: Mon Jan 22, 2007 12:05 pm    Post subject:
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Hi Sasi,

I assume you are asking about the diffrence between a Join and an exists check for a matching record..

From the feedbacks I ve got from DBA's, it seems an EXISTS check is better if do not require a column from the table to be selected. But if you need a column from the table to be selected, better to use JOIN.

Please let me know if I am not answering your question.

Thx,
Prajesh
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