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Any value in unique index option?
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Information générale
Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Divers
Thread ID:
00130650
Message ID:
00130660
Vues:
16
Jim,

That's a good example of using unique indexes, but wouldn't SELECT DISTINCE State FROM customer be faster and easier in most cases?

>>Does anyone know of a valid reason for using the Unique index type? If there are duplicates, you should use Reqular and if they are truly key fields then Primary or Candidate should be used. (IMNSHO)
>>
>>Is it there for backward compatibility? There's nothing I've found to that effect.
>>
>>Thanks,
>
>Rock,
>
>Unique indexes should only be used as temporary indexes. For example, assume you ahve a customer table with 50,000 records in it and you want a list of states that you have custoemrs in, you can;
>
>USE Customer
>INDEX ON State TAG Temp UNIQUE
>* Print your states listing
>DELETE TAG Temp
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