At 12:40 PM 19-06-01 -0400, you wrote:

>A customer converting from Oracle has a (horrible,
>massive, badly performing) query that includes
>something like this:
>
>select x from foo
> where exists (select 1 from foo where x > 10
> union
> select 1 from foo where x < 10)
>
>(I know that's an idiotic query - it's the syntax
>I'm worried about at the moment.)
>
>The DSQL parser spits up when it encounters the
>union, just as if it thought that you couldn't
>have a UNION clause in a subquery. My recent
>web surf has failed to enlighten me, and I'm quite
>sure I'm confusing the rules about updateable views
>with the rules about subqueries.
>
>Does anyone know whether union clauses are allowed
>in subqueries according to the SQL-99 or SQL-92
>standards, any level?

My SQL book isn't committing itself except to indicate that SQL-92 introduced a lot more "orthogonality" into subqueries (whatever that means). (I thought it meant a state of having four interior right angles..)

And thank you for sharing it with us. :))

Helen

All for Open and Open for All
InterBase Developer Initiative · http://www.interbase2000.org
_______________________________________________________