can we make a cross reference from doc 4.4.1( http://www.postgresql.org/docs/devel/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS ) to doc 7.3.2 ( http://www.postgresql.org/docs/devel/static/queries-select-lists.html#QUERIES-COLUMN-LABELS ) *to mention that “AS” can make a key word to be a identifier?* I have read the doc 4.4.1 and can't find this info from there so I thin it is a bug.
2013/2/22 Jov <am...@amutu.com> > I have get the description of this behaviour from doc 7.3.2 > > http://www.postgresql.org/docs/devel/static/queries-select-lists.html#QUERIES-COLUMN-LABELS > . > > from the error message now,I think syntax error may emmit by the > parser,parser error make it hard to get the really condition such as the > second token ‘end’ is a select item from a select statement. > > thanks > > 2013/2/22 Tom Lane <t...@sss.pgh.pa.us> > >> "=?ISO-8859-1?B?Sm92?=" <am...@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 >> . >> >> > > > -- > Jov > blog: http:amutu.com/blog <http://amutu.com/blog> > -- Jov blog: http:amutu.com/blog <http://amutu.com/blog>
