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Data selecting velocity
Message
De
06/04/1998 12:04:39
Cetin Basoz
Engineerica Inc.
Izmir, Turquie
 
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Divers
Thread ID:
00089851
Message ID:
00089856
Vues:
30
>Hello, can I ask You a question?
>Why does REQUERY function work much longer than SELECT-SQL command and
>the BROWSE command from the View menu in the case of large number of
>records in the the base table (more than 50000)?
>
>Code:
>SELECT * FROM db_price!pricelst ;
>WHERE LEFT( pricelst.code, ?gnKeyCurrentLength ) BETWEEN ?guRangeLow ;
> AND ?guRangeHigh ;
>AND SUBSTR( PriceLst.Code, ?gnRemainStart, ?gnRemainLength ) = ;
> ?guRemainFill ;
>ORDER BY code
>
>Processing time of SELECT-SQL command is less than 1 second, but in the case of using REQUERY() function it consists 70-80 seconds.
>
>Can I do anything to accelerate this process?
>
>Excuse me for bad English.
There are differences but not to this extent. Now to accelarate it:
LEFT( pricelst.code, ?gnKeyCurrentLength ) BETWEEN ?guRangeLow ;
AND ?guRangeHigh ;
Should be replaced by :
pricelst.code between BETWEEN ?guRangeLow ;
AND ?guRangeHigh ;
So it could benefit a code index (set exact off).
Cetin
Çetin Basöz

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