Re: A simple join question that may stump you

Ross,

> ID FLAG
> ----- -----
> 1 1
> 2 1
> 2 2
> 3 1
> 3 2
> 3 3
>
> and table B:
>
> FLAG
> -----
> 1
> 2
>
> I want to find all id's from table A that have every flag in table B
> but no extra flags. So, I'd end up with:
>
> ID
> -----
> 2

Try looking at the INTERSECT and EXCEPT join types. Thus, in pseudo-sql
you'd need:

SELECT A.ID
WHERE Count A JOIN B = Count B
AND Count A EXCEPT B = 0

Assuming that all rows in A are unique.

-Josh

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