Re: Avoid multiple scan of the same table

maks71_at_gmail.com wrote:
> Is there way to avoid multiple scan of the same table in following?
>
> Select c1 as v1, c2 as v2, c3 as v3
> From t1
> Union
> Select c1 as v1, c2 as v2, c4 as v3
> From t1
> Where c5 < 5000
>
> The output should look like..
>
> v1, v2, v3
> v11, v21, v31
> v12, v22, v32
> and so on.
>
> Rows from the both queries can be same so UNION is required to avoid
> duplicates in current construct.

So rows with c5<5000 are supposed to be returned twice, except when c3 and c4 happen to be the same, then it should only be returned once?

Xho

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