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Is UNION acceptable in a View?
Message
De
17/03/2001 01:23:19
 
 
À
16/03/2001 08:53:54
Cindy Winegarden
Duke University Medical Center
Durham, Caroline du Nord, États-Unis
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Divers
Thread ID:
00485727
Message ID:
00486220
Vues:
11
>>It's legal to use UNIONs in a view, as long as it's defined with CREATE SQL VIEW and you don't later attempt to modify it with the VFP View Designer.
>>
>>However...
>>
>>Is it good practice to use UNION clause(s) in a view? Or, is that usually a sign that the database should be refactored?
>
>I think using UNION may be a (good) sign that the database is successuflly normalized. Usually views are used to denormalize data for particular uses, such as querying or reporting.

Hmmm... in my experience having to use UNIONs (whether in a view, or straight SQL) is a sign of DB design problems. Usually along the lines of the designer believing entities were apples, oranges, bananas, and kiwi fruits, when really they were Fuji, Spartan, Granny Smith and McIntosh apples.
Regards. Al

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