Re: Storing where clause
Date: Fri, 20 Aug 2004 11:36:28 -0400
Message-ID: <gb2dnbkqHtFkhLvcRVn-vA_at_comcast.com>
"Nagraj Kini" <snakess_at_hotmail.com> wrote in message
news:451a6377.0408192357.5a63dc5d_at_posting.google.com...
> Right now the where clause is stored as a string which I am not too
> thrilled about. I want to provide a UI so that the application admin
> can himself add the where clause
The object of the where clause is a predicte. A predicate is an expression. An expression can be expressed as a tree using operators or functions as the nodes, and variables, parameters or literal values as the leaves. A tree can be expressed in relational terms using the methods Joe Celko has written extensively about.
A partial list of operators follows:
Logical operators like "and", "or", and "not".
Comparators like "equal to" and "less than".
Arithmetic operators like "+", "-", "*", and "/".
String operators like "concatenate".
Pattern matching operators like "like".
Having said all that... What's so bad about the application admin having to know the language of predicate expressions, and having to edit a string?
And this is off topic... I'm intrigued by the fact that you said "application admin" rather than "DBA". About ten years ago I worked at a site where there was an application admin, and I was the DBA. I'm interested in how those roles are differentiated, in your view. Received on Fri Aug 20 2004 - 17:36:28 CEST