--- Gary Benade wrote:
Say I have a table TEMP containing the values 1,2,3,4

SELECT * FROM LARGETABLE WHERE MAININDEXVALUE IN (1,2,3,4)

SELECT * FROM LARGETABLE WHERE MAININDEXVALUE IN ( SELECT * FROM TEMP)

Does the second statement get optimised to execute as efficiently as the
first, or is there a performance penalty?


Hi Gary.

Assume Temp containts a field ID, the primary key, then the query would
be best written:

select
L.*
from
LargeTable L
where
L.MainIndexValue = (
select
T.ID
from
Temp T
where
T.ID = L.MainIndexValue
)

That would pan out more efficiently I believe.

Regards,

Ian.



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