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Message Posted: Tue, 25 Mar 2003 @ 11:39:11 GMT


     
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Subj:   Re: Teradata sql and range value queries
 
From:   Dieter Nöth

  2) subquery's seem to support the ansi-99 standard syntax, but underneath, just join the the nested and outside tables together on the common column...instead of running the outside query once for each value returned by the subquery query. Is there a workaround for this too?  



The standard says nothing about how a subquery has to be performed by a DBMS. And it's an advantage that you don't have to think about several ways to write a query.

In Teradata there usually is no difference if you write a query using a join, a subquery or a correlated subquery, it's the same optimized plan. This is no bug it's really a feature ;-) It's called query rewrite.


Dieter



     
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