Op 21 jul 2013, om 18:06 heeft Simon Slavin het volgende geschreven:
On 21 Jul 2013, at 4:41pm, E.Pasma <pasm...@concepts.nl> wrote:
Is a change in SQLite imaginable such that column expressions are
not re-evaluated with each reference to the column alias?
...
... This is partly because the order of evaluation of terms in a
SELECT is not defined: SQL permits those three values to be
evaluated in any order. ...
Your suggestion introduces a new requirement on how SQL works that
it must figure out the "AS" expressions first. Which might do
nicely for your example but it would cause delays in other commands.
That is a plausible reason.
Just one more thought with respect to the originally posted query:
select 7 as a, 8 as b, a / b as c;
This might then as well be accepted by sqlite as if it occured in the
order by clause.
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