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Tuning SQL statement
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De
09/09/2004 12:39:20
 
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00940327
Message ID:
00940705
Vues:
19
>Make sure you've indexes on all fields used in JOINs. Quick loock revealed that you don't have indexes in the Termcourse table for following joins
...
>   ON  Termcourse.roomid = Roomslist.roomid ;
>    INNER JOIN smagic!schedulehours ;
>   ON  Termcourse.hourid = Schedulehours.hourid ;
>    INNER JOIN smagic!teacherlist ;
>   ON  Termcourse.teacherid = Teacherlist.teacherid;
>...
>
I added those, but it's still not so good. I think what's causing it is
>>Joining table schedulehours and table termcourse (Cartesian product)
>>Joining intermediate result and table roomslist (Cartesian product)
>>Joining intermediate result and table programlist (Cartesian product)
>>Joining intermediate result and table teacherlist (Cartesian product)
>>Joining intermediate result and table courses (Cartesian product)
>>Joining intermediate result and table courselist (Cartesian product)
>>Joining intermediate result and table enroll (Cartesian product)
>>Joining intermediate result and table attendance (Cartesian product)
>>Joining intermediate result and table person (Cartesian product)
these Cartesian joins. The WHERE Termcourse.crsschedid = (?vp_crsschedid) will filter it down to the 29 record result, so how do I make it evaluate the where clause early?
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