Re: SQL92 compliance

Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> Am Mittwoch, 23. August 2006 03:40 schrieb Daniel CAUNE:
>> Is AS in "SELECT my_column AS my_name FROM my_table" mandatory to be SQL92
>> compliant?

> No. I have a patch at
> <http://developer.postgresql.org/~petere/select-without-as/select-without-as.patch>
> that fixes this at least for 7.4.

I think it's a big stretch to say that that patch fixes it, since it
only allows an AS-less target expression to be c_expr rather than
a_expr as it ought to.

The problem is really insoluble given that we allow user-defined
postfix operators: is "SELECT x ~~ y" meant to be an infix operator
with arguments x and y, or a postfix operator with argument x and
a column label y?

When this has come up in the past, we've always concluded that
compliance with this not-very-well-thought-out detail of the spec
is not worth the price of giving up postfix operators.

Even if we were willing to do that, I think we'd also have to give
up using bison to generate the parser :-( because some constructs
would require more than one-token lookahead.

regards, tom lane