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The best way to use a portion of a field for indexing
Message
De
11/01/2005 05:43:08
 
 
À
10/01/2005 22:10:35
Walter Meester
HoogkarspelPays-Bas
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Versions des environnements
Visual FoxPro:
VFP 6 SP5
OS:
Windows XP SP2
Network:
Windows 2000 Server
Database:
Visual FoxPro
Divers
Thread ID:
00975802
Message ID:
00975966
Vues:
25
>Hi Tore,
>
>>Remove the ALLTRIM function!!! NEVER, NEVER, NEVER use ALLTRIM in an index expression! And this rule has NO exceptions!
>
>NEVER SAY NEVER :) . The rule is that each index expression should has the same fixed length. ALLTRIM() certainly is a threat but an index expression of:
>
>
INDEX ON PADR(ALLTRIM(FirstName)+ALLTRIM(LastName),40)
>
>is perfectly valid.
>
>Walter,

Why PADR ?

It is unnecessary.
CREATE CURSOR byby (c c(2))
INDEX on ALLTRIM(C)+ALLTRIM(C) TAG t1 && VFP build a key with LEN(KEY())=FSIZE('C')+FSIZE('C')
? SEEK('11')
INSERT INTO byby VALUES ('12')
INSERT INTO byby VALUES (' 2')
? SEEK('1212')
? SEEK('22')
Fabio
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