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Possible Duplicate:
Explicit vs implicit SQL joins
Stmt1: SELECT ... FROM ((a JOIN b ON <cond1>) JOIN c ON <cond2>)
Stmt2: SELECT ... FROM a, b, c WHERE <cond1> AND <cond2>
I’m not sure whether the second statement can give a smaller resultset. If there are several rows in B matching to one row in A, do we get all these matches with the second statement?
As a final result, yes.
Regarding the execution: the query optimizer might end up creating the same query execution plan for both queries.
This will be the case if, according to its approximate statistics (approximate equi-depth histograms for instance – which are not all the time up-to-date, by the way), the optimizer will determine that the first join is more selective than the second one and, consequently, it will execute this one first.
Stmt1 allows you to specify the order of the joins and, considering that you know exactly what the tables contain, this might be a better solution.