Re: ??Difference between JOINs

vurley wrote:
>
> Would anybody tell me what is the difference between Nested Loop Join, Hash
> Join and Sort Merge Join. Thanks in advance.

(In brief)

Nested loop

• scan one table and use its data to look up the other ( hopefully with an index)

Merge Join
- sort both tables, merge the result, look for dups - these are the join rows

Hash join
- take a small table, hash the values, link to larger table

HTH

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Connor McDonald
http://www.oracledba.co.uk

We are born naked, wet and hungry...then things get worse