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Forum:
Visual FoxPro
Catégorie:
Codage, syntaxe et commandes
Titre:
Divers
Thread ID:
00171828
Message ID:
00171992
Vues:
32
>I suspect I don't fully understand their (surrogate keys) utility. I'll have
>to get one of the wunderkinder to explain it to me sometime.

Well, there are two main reasons. One is joins: a 4-byte integer key is a lot faster than, say, an 11-byte character SSN. The other reason is uniqueness: if you create a view on an order detail table, do you want to have to have the concept of order detail line number, so that you have a composite key (order + linenum), or just stick a 4-byte number at the beginning of each line? (not that this example really proves my point, but...)
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