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How to use index
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Information générale
Forum:
Visual Basic
Catégorie:
Bases de données DAO/RDO/ODBC/ADO
Divers
Thread ID:
00743351
Message ID:
00743458
Vues:
10
Hi Winan. To be honest, this is a better question for the SQL Server forum if you want more details. In fact, I have taken the liberty of starting a new thread over there.

>Thanks for your quick reply, you mean that I have to change the >open "Table" statement to open "Select * from blahblah where blah blah >= ..." ?

Yes, that is what I mean.

>if "Yes".. my question is how about the indexes that I created ? are they >automatically use by the system regarding my "Order by .." statement .. ? >or if "Not" how to use it .. ?
>

Well, it's pretty much automatic for the selection criteria and the join. (That's a bit oversimplified -- there are certain expressions and approaches which will not make use of an index, and the best thing to do is run the query in Query Analyzer with "Show Execution Plan" on and see that it's using the index.)

I'll be honest -- I am not sure if the ORDER BY part actually uses an index. I just did a quick test and it seems that if I order on the clustered index no additional sorting is necessary (this is no a surpise). But, if I order on a non-clustered index, the execution plan looks identical (and the cost of the ordering identical) to a case where I order on a non-indexed field.
The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts. - Bertrand Russell
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