Rows default order in UNION ALL mysql clause?.. Which row would be fetched first, I mean?

Question

If I, for example, have a real simple query:

SELECT 1 UNION ALL SELECT 2

and then fetch rows via Perl or PHP - would I have "1" as a FIRST row, and "2" as a SECOND? Is this behaviour described anywhere?..

Thanx

Answer 1

There's no default order, not in tables and not in queries, unless you specify an explicit order with ORDER BY.

You would probably have 1 as first row, and 2 as second, but it's not default behaviour and it's not described anywhere. It's just coincidence!