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Re: UNION + INTO OUTFILE is confusing
On May 04, Alexander Barkov wrote:
> If I run this query:
> SELECT 1 UNION SELECT 2 INTO OUTFILE 'test.txt';
> It creates a file 'test.txt' with this content:
> Looks fine so far.
> Now if I do "rm test.txt" and execute another query (with parentheses):
> (SELECT 1) UNION (SELECT 2 INTO OUTFILE 'test.txt');
> it still puts the same two records from both UNION parts!
> This looks confusing, as parentheses a kind of assume that only
> the right UNION part is to be exported.
> Exporting only one UNION part is not supported, IIRC.
> So the above query should probably return a syntax error.
Hardly. It'll break existing applications that export UNION result into
a file. For no good reason.
> But now there is a new trouble. There is no syntax like this:
> (SELECT ...) UNION (SELECT ...) INTO OUTFILE 'test.txt';
This one we can support, perhaps. Or may be not, SELECT ... INTO is
non-standard anyway, so I wouldn't bother...
> So instead of:
> (SELECT ...) UNION (SELECT ... INTO OUTFILE 'test.txt');
> one will have to write this:
> SELECT * INTO OUTFILE 'test.txt'
> FROM ((SELECT ...) UNION (SELECT ...)) AS t1;
Chief Architect MariaDB