"Jov" <amutu@amutu.com> writes:
> xxx=# select end from (select 1 as end) t;
> ERROR: syntax error at or near "end"
> LINE 1: select end from (select 1 as end) t;
> ^
You need to double-quote the outer use of "end", viz
regression=# select "end" from (select 1 as end) t;end
----- 1
(1 row)
In the context with "as", Postgres can tell the word is meant as a
column identifier not a keyword, but there's no way for it to know that
in the outer usage.
> I think use key word as alias should get a error message such as $key_word
> is Key Word,should not be used as identifier bla bla,so for some complex
> query error user can save a lot of time.
Well, yours is the first complaint we've ever had in that direction,
whereas we used to get a lot of complaints in the opposite direction,
back when we didn't allow keywords to be used for column names.
So I doubt we'll change it. It is an interesting gotcha though :-(
regards, tom lane