Re: Show/Explain Query Plan

I think you can guess what is the execution path of SQL Server running the following query.

select * from table1 where col1 <> col1

Dan Guzman (nospamplease_guzmanda_at_mindspring.com) wrote:
: Ng K C Paul wrote in message <6tvoo6$dti$2_at_imsp009a.netvigator.com>...
: >I always think that the where clause is the row filtering criteria
: >
:
: By 'row filtering criteria', I meant column references in the where clause.
: The where clause in question contains only literals so it is the rows from
: the result set that are filtered, not individual table rows. No indexes
: will be taken into account in the generation of the execution plan
: because.there is no criteria placed on individual table rows.
:
: The point I was trying to make is that the query plan (at least with MSSQL
: Server 6.5) does not show that the boolean condition seems to be evaluated
: before the table scan actually takes place so the query will run
: instantaneously regardless of the size of the table as long as the condition
: is false. If condition is true, a table scan will occur, as it should due
: to the absence of row filtering criteria.
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Received on Sat Sep 19 1998 - 00:00:00 CDT