Optimalization - 3 SELECTs with one condition OR one SELECT with three conditions

Hello everyone.
I have got a simple question, but very important for me.
I making a quite big report and I have a lot of conditions to compare.
And I wonder, what is faster:
One SELECT statement with three comparing conditions
OR
Three SELECTS, each with one comparing condition
All the conditions are separated by AND condition.
The Store Procedure is being made on MS SQL SERVER 2000, the size of
table is around 22098165 records.
Thanks a lot for help... marianowic> And I wonder, what is faster:
> One SELECT statement with three comparing conditions
> OR
> Three SELECTS, each with one comparing condition
> All the conditions are separated by AND condition.
How will 3 independent SELECT statements to provide the desired results with
AND conditions? I would expect the single statement approach to be best.
Performance largely depends on available indexes.
Hope this helps.
Dan Guzman
SQL Server MVP
"marianowic" <marianowic@.gmail.com> wrote in message
news:1179398916.316799.118410@.h2g2000hsg.googlegroups.com...
> Hello everyone.
> I have got a simple question, but very important for me.
> I making a quite big report and I have a lot of conditions to compare.
> And I wonder, what is faster:
> One SELECT statement with three comparing conditions
> OR
> Three SELECTS, each with one comparing condition
> All the conditions are separated by AND condition.
> The Store Procedure is being made on MS SQL SERVER 2000, the size of
> table is around 22098165 records.
> Thanks a lot for help... marianowic
>|||If you (due to lack of indexes or the nature of the queries) have to read in
the full table for any of the three, then I would bet it is more efficient
to combine everything into one query since it is ALWAYS more efficient to
read data once than multiple times. I/O is the biggest reason for
performance issues.
However, if your 3 queries each use different indexes and hit different
sections of the tables, then a multi-statement approach may be best.
I will agree with other posters that we can't help you very much with such
limited information.
TheSQLGuru
President
Indicium Resources, Inc.
"marianowic" <marianowic@.gmail.com> wrote in message
news:1179398916.316799.118410@.h2g2000hsg.googlegroups.com...
> Hello everyone.
> I have got a simple question, but very important for me.
> I making a quite big report and I have a lot of conditions to compare.
> And I wonder, what is faster:
> One SELECT statement with three comparing conditions
> OR
> Three SELECTS, each with one comparing condition
> All the conditions are separated by AND condition.
> The Store Procedure is being made on MS SQL SERVER 2000, the size of
> table is around 22098165 records.
> Thanks a lot for help... marianowic
>|||> I have got a simple question, but very important for me.
ok

> And I wonder, what is faster:
> One SELECT statement with three comparing conditions
> OR
> Three SELECTS, each with one comparing condition
If you have 3 selects, do you use them all in one report? If yes, then
it does not matter if you use 1 or 3 selects, you will end up with lot
of records.