On Thu, Aug 25, 2005 at 09:53:26AM +0100, THIBAULT Jean-Jacques wrote:
>
> this query work :
> select null UNION 1;

Please show the *exact* query. The above produces a syntax error:

test=> select null UNION 1;
ERROR: syntax error at or near "1" at character 19
LINE 1: select null UNION 1;
^

I suspect this is the actual query:

test=> select null UNION select 1;
?column?
----------
1

(2 rows)

> this query doesn't work :
> select null UNION null UNION 1;
>
> ERROR: UNION types text and integer cannot be matched

Again, the query as written causes a syntax error. This is probably
the actual query:

test=> select null UNION select null UNION select 1;
ERROR: UNION types text and integer cannot be matched

To understand what's happening, see "UNION, CASE, and ARRAY Type
Resolution" in the "Type Conversion" chapter of the documentation:

http://www.postgresql.org/docs/8.0/s...nion-case.html

--
Michael Fuhr

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