Fantastic!!

Thanks Arno !

eLita
--- Arno Brinkman <firebird@...> wrote:

> Hi,
>
> > Is there any maximum number of union in a query?
>
> Not directly UNION, but the number of streams
> (255).
> Every tables uses 1 stream and every UNION uses 1
> stream, thus
>
> Example1:
>
> SELECT * FROM RDB$DATABASE
> UNION ALL
> SELECT * FROM RDB$DATABASE
>
> uses 3 streams
>
>
> Example2:
>
> SELECT * FROM RDB$DATABASE
> UNION ALL
> SELECT * FROM RDB$DATABASE
> UNION ALL
> SELECT * FROM RDB$DATABASE
> UNION ALL
> SELECT * FROM RDB$DATABASE
>
> uses 7 streams
>
>
> Example3:
>
> SELECT
> *
> FROM
> RDB$RELATIONS r
> JOIN RDB$RELATION_FIELDS rf ON
> (rf.RDB$RELATION_NAME = r.RDB$RELATION_NAME)
> UNION ALL
> SELECT
> *
> FROM
> RDB$RELATIONS r
> JOIN RDB$RELATION_FIELDS rf ON
> (rf.RDB$RELATION_NAME = r.RDB$RELATION_NAME)
>
> uses 5 streams
>
>
>

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