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[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Alexander!

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:
> 
> 1
> 2
> 
> 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;

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx