Re: Aliases for Field Names in SELECT statements

>>>>> "Randal" == Randal L Schwartz <merlyn(at)stonehenge(dot)com> writes:

>>>>> "Rich" == Rich Shepard <rshepard(at)appl-ecosys(dot)com> writes:
Rich> A thread on the postgres users mail list asks how to write a SELECT
Rich> statement using a column alias (e.g., SELECT emp_id AS e FROM employee),
Rich> and Bruce Momjian responded that it's not possible and on the To-Do list
Rich> to not be done.

Randal> Are you sure he wasn't talking about the fact that in the standard, aliases
Randal> apply *after* the WHERE, but *before* the HAVING, and therefore you can't ever
Randal> use aliases in the WHERE clause since they simply don't exist yet?

Ahh, just checked out the thread. The problem is not the aliases: they're
fully supported according to the spec.

The problem is the optional "AS" keyword. Other SQLs permit:

SELECT foo bar FROM atable;

to mean

SELECT foo AS bar FROM atable;

The problem is that permitting optional "AS" means that Pg with its
unique postfix operators would be ambiguous. If + was a postfix
operator, would:

SELECT foo + bar FROM atable;

mean that "foo +" is being aliased to bar, or that the column is
foo + bar?

Interesting problem.

--
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