Re: Determining if a bit is set
From: Joe Celko (jcelko212_at_earthlink.net)
Date: 07/20/04
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Date: Tue, 20 Jul 2004 15:03:23 -0700
>> I have a class of things which I describe as a record [sic] in a
table. There are certain attributes of this class [sic] that are not
mutually exclusive. If I know what these attributes are, it is probably
best to let each one be a field [sic], but if the list of these
attributes can go (or shrink) at the will of the user, it seems best to
me to simply tag each attribute with an index and sum all the indexes in
one field [sic] to determine which attributes the particular class
instance posesses. Is there a better way to do this? <<
Let's get back to the basics of an RDBMS. Rows are not records; fields
are not columns; tables are not files; there are no classes in the OO
sense of the word. In short, you are not talking our language.
An unknown number of attributes means you have no data model or schema
design. BY DEFINITION a table knows all its attribute. Then letting
users design a schema on the fly at run time is dangerous as hell. YOU
are the programmer; this is YOUR job, not their's.
This sounds like you are still doing requirement analysis and you can
use a notebook or text tool for this.
--CELKO--
===========================
Please post DDL, so that people do not have to guess what the keys,
constraints, Declarative Referential Integrity, datatypes, etc. in your
schema are.
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