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Help Optimizing a query
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À
09/08/2001 20:18:40
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00542086
Message ID:
00542089
Vues:
22
Dan,

You don't need
        Not Empty( Ramp ) And ;
        <b>Not</b> Empty( HourCount ) ;
because it's covered by
        Upper( Ramp ) = 'CHICAGO' And ;
        Between( HourCount, 37, 48 ) And ;
Also expression Empty(Somefield) isn't rushmore optimizable. Use Somefield = Space(nn) instead.

>I have six conditions in my where clause.
>Upper( Ramp ) returns 27,705
>Between( HourCount, 37, 48 ) returns 147,711
>Upper( Vendor ) returns 555,784
>Not Empty( Ramp ) returns 957,731
>Not Empty( HourCount ) returns 957,731
>
>The table has 1,166,384 records.
>I have an index on Upper( Vendor )
>I have an index on Upper( Ramp )
>I have an index on HourCount.
>
>I do not have an index on Empty( Ramp )
>I do not have an index on Empty( HourCount )
>
>I am using variables but the with the above example the SQL looks like:
>
>Select ;
>        Ramp, ;
>        Vendor, ;
>        VendCity, ;
>        VendSt, ;
>        HourCount ;
>    Where ;
>        Upper( Ramp ) = 'CHICAGO' And ;
>        Between( HourCount, 37, 48 ) And ;
>        Upper( Vendor ) = 'NIKE' And ;
>        Not Empty( Ramp ) And ;
>        Empty( HourCount ) ;
>    Into Cursor qVendorTimes NoFilter
>
>
>I'm afraid to break the SQL down into multiple SQL's because writing out 27,000 records is going to be slow.
>
>Please help me.
>
>TIA
--sb--
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