sql - Performance impacts on specifying multiple columns in inner join -

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i want select records 2 tables based on matching values of 2 columns. have got 2 queries same, out of these 1 contains join on 2 columns as:

    select           *             user_master um     inner join         user_location ul     on          um.customer_id=ul.customer_id , um.created_by=ul.user_id

and same results can achieved following query having single column join as:

    select              *             user_master um     inner join         user_location ul     on          um.created_by=ul.user_id             um.customer_id=ul.customer_id

is there difference in performance of above queries?

as concerning performance answer is: depends.

in general engine smart enough optimize both queries, i'm not surprised if both produce same execution plan.

in fact must run both queries few times , study execution plan determine if both run same time and using same amount of cpu, io , memory. (remember performance not running fast, smart use of resources).

for "semantic" vision, data using 2 keys "determined". in case can let both expression @ join predicate. let filters @ clause. advantage of explicit joins on implicit ones create logic (and visual) separation


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