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Deleted Records showing
Message
De
23/02/2010 14:31:45
 
 
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Versions des environnements
Visual FoxPro:
VFP 9 SP1
Divers
Thread ID:
01450510
Message ID:
01450557
Vues:
37
>>"Real" DBMS don't have deleted records at all, instead the records are flagged as reusable, and reused whenever necessary. They also don't have "record numbers". Do you know any other DBMS than xBase which has a "recall" command?
>
>I don't know of any other such database having recall functionality. In any other database I know the deleted records can only be taken from last backup.

Exactly, the space they occupy is internally marked as reusable, and not visible to the outside worlds. When you add new records, the reusable records are used as long as there are any available. That's how most DBMS work, xBase is the only DBMS I know which gives the user direct control over each record, so to say. Whether it's a good thing or a bad thing, that's up to the programmers to decide. I don't like it, and have business logic to reuse the reusable records, just like most DBMS work. Maybe that's one of the reasons why I never experience table corruption?
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