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If I submit a query to SQL Server 2005 which contains a number of LEFT JOIN clauses where the table joined to is then never referenced, will the joins still happen or is SQL Server intelligent enough to discard them?
Obviously it wouldn’t be able to discard INNER JOINs [false assumption! see answers] as that would potentially change the result, but can it do it for LEFT JOINs?
A left join could potentially multiply your result set if there are many matches.
So therefore it would still be evaluated.