Re: Re: [SQL] aliases break my query

Tom Lane writes:

> "Zeugswetter Andreas" <andreas.zeugswetter@telecom.at> writes:
> > I think we could get agreement to not allow implicit from entries 
> > if there is a from clause in the statement, but allow them if a from clause
> > is missing altogether.

That's what I had in mind.

> "Emit a notice [or error if you insist] when an implicit FROM item is
> added that refers to the same underlying table as any existing FROM
> item."

That's a step in the right direction, but I'd still like to catch

SELECT a.a1, b.b1 FROM a;

SELECT a.a1 FROM a WHERE a.a2 = b.b1;

both of which are more or less obviously incorrect and easily fixed.

> 95% of the complaints I can remember seeing were from people who got
> confused by the behavior of "FROM table alias" combined with a reference
> like "table.column".  Seems to me the above rule would catch this case
> without being obtrusive in the useful cases.  Comments?


-- 
Peter Eisentraut                  Sernanders väg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden