conditions in where; the order

  • Thread starter Thread starter alekm
  • Start date Start date
A

alekm

Hi,
I'd like to know which condition in where part of sql will be considered
first. I'd like to optimize sqls.
For example: select * from table t where condition1 and condition2 and
condition3

thank you in advance

alekmil
 
The result will be the same in the end but time spent will not be same I
guess. I tought of making sql faster when I said optimize.
 
Hi Bruce,

In older versions of Oracle, the order could matter. Basically the last part
of the Where statement was evaluated first. However never versions of Oracle
use query optimization to run queries how Oracle thinks best. Access does the
same thing. Basically the first time you run a query, it might be slower as
Access is figuring out how to run it faster in the future. That's why any
time you are putting a stopwatch against a form, report, or query, you should
run it twice after messing with the SQL. The second and subsequent times will
probably be faster.

This was cross-posted to another forum and I suggested that alekm use the
Jet Showplan to check how a query actually runs.
--
Jerry Whittle, Microsoft Access MVP
Light. Strong. Cheap. Pick two. Keith Bontrager - Bicycle Builder.


BruceM via AccessMonster.com said:
Why do you guess the time will not be the same?
The result will be the same in the end but time spent will not be same I
guess. I tought of making sql faster when I said optimize.
Unless I'm missing something in your question it doesn't matter. I suppose
the first one will be "considered" first, but a search of the parking lot for
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alekmil
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Message posted via AccessMonster.com


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