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Message Posted: Fri, 27 Feb 2004 @ 22:46:20 GMT
On Fri, 27 Feb 2004 16:25:18 -0500, Meade, Cornelius wrote:
Perhaps my comment was unclear. I see two aspects with derived tables:
1. SQL syntax form;
2. performance enhancement tool.
1. It looks like this new syntax form proved to be useful and it has been adopted by ANSI. In Oracle, derived tables are known as "inline views" and have been around for some time. SQL Server supports them too. So, as a syntax form these "unnamed views" are likely to stay. I agree with you here.
2. I think in the future database vendors won't promote derived tables as performance enhancement tools. They will become a normal part of SQL, just as views, subqueries, predicates etc. As with other SQL elements they may or may not improve performance. It will be more up to the optimizers whether to use derived tables internally or just completely rewrite the statement and forget about them.
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