RE: Astonished by embedded sql

On Tue, 2010-10-12 at 07:41 -0500, Kevin Bucknum wrote:

Since the original programmer is reading one record with an sql
statement with no ordering and then exiting, then a chain should get the
same record as he is getting anyways. Unless sql doesn't respect
LIFO/FIFO/FCFO.

I believe that all the query interfaces (SQL, OPNQRYF, QUERY/400)
carefully refrain from guaranteeing any sequence not specified
explicitly. It is just by luck--good luck, or bad luck, you can choose
which you like--that we often get the sequence we were thinking about.

<aside attitude="rueful">
I remember, long ago, that I keyed the very first record with a date
in 2000 into a file, and then a downstream report suddenly looked
really, grossly different. It took entirely too long to verify that
the changed result had nothing to do with date; it was merely that
one additional record made the query optimizer choose an entirely
different strategy. For decades, the report had been delivering the
right result *by accident*. (Thank you for letting me give this hobby
horse some exercise.)
</aside>

HTH,
Terry.