Bonjour Vik,
Is quoting the spec good enough?
SQL:2016 Part 2 Foundation Section 7.10 <joined table>:
Ah, this is the one information I did not have when reviewing Peter's
patch.
<named columns join> ::=
USING <left paren> <join column list> <right paren> [ AS <join correlation
name> ]
<join correlation name> ::=
<correlation name>
I think possibly what the spec says (and that neither my patch nor
Peter's implements) is assigning the alias just to the <join column
list>.
I think you are right, the alias is only on the identical columns.
It solves the issue I raised about inaccessible attributes, and explains
why it is only available with USING and no other join variants.
So my original example query should actually be:
SELECT a.x, b.y, j.z FROM a INNER JOIN b USING (z) AS j;
Yep, only z should be in j, it is really just about the USING clause.
--
Fabien.
