Re: Diff. between UNION and UNION ALL

Union- issued an implicit 'distinct' rows which requires sorting, i.e. a longer process

Union all- implies select * from a then append select * from b to the bottom.

EX:

A	B
-	-
1	1
2
3	3

union = (1,2,3)
union all = (1,2,3,1,3)

>
>What's the difference between UNION and UNION ALL (in a SELECT
>statement). I don't find any info on this in the Oracle manuals. Would
>some explain this with a simple example.
Received on Sun Mar 02 1997 - 00:00:00 CST