> [...] but OTOH "\if sql 1 from table where expr" looks awkward. Given an
> implicit select, I would prefer "\if exists (select 1 from table where
> expr)" but now it's not shorter.
Possibly, but it is just an SQL expression, which looks good in the middle
of an sql script.
> An advantage of prepending the SELECT automatically, is that it
> would prevent people from abusing this syntax by putting
> update/insert/delete or even DDL in there, imagining that this would
> be a success/failure test for these operations.
> Having these fail to execute in the first place, when called by \if,
> seems like a sane failure mode that we would gain incidentally.
Yes, it should be avoided.
--
Fabien.