On 13/04/11 19:32, Tom Lane wrote:
"Jeff Wu"<j...@atlassian.com> writes:
The UNION construct (as noted on this page:
http://www.postgresql.org/docs/9.0/static/typeconv-union-case.html) will
cast unknown types to TEXT, however, if you try to do three or more UNIONs
the order in which the UNIONs are executed will cause some columns to be
cast to TEXT prematurely. The result is a type mismatch error.
<snip>
Or maybe we could find out that some other products
do it like that despite what the spec says?
regards, tom lane
I happen to have a MS SQLServer 2008 instance at work as well as a MySQL
5.1 and an Oracle 10g. With the query:
SELECT 1,null,null
UNION
SELECT 2,3,null
UNION
SELECT 3,null,4
In MS SQLServer I get (NB: no column headings):
----------------------
----------------------
1 | <null> | <null>
2 | 3 | <null>
3 | <null> | 4
In MySQL I get:
--------------------
1 | NULL | NULL
--------------------
1 | <null> | <null>
2 | 3 | <null>
3 | <null> | 4
In Oracle I get a delicious error message:
Error: ORA-00923: FROM keyword not found where expected
SQLState: 42000
ErrorCode: 923
Position: 19
Regards,
--
Mike Fowler
Registered Linux user: 379787
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