Re: alias required by standard or PostgreSQL?

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

"Joost Kraaijeveld" <J(dot)Kraaijeveld(at)Askesis(dot)nl> writes:
> "select * from (select * from table_name)" 

> PostgreSQL complains with 

> ERROR:  subquery in FROM must have an alias
> HINT:  For example, FROM (SELECT ...) [AS] foo.

> Is the alias required by the ISO standard

Yes.  A FROM-clause entry is defined as

         <table reference> ::=
                <table name> [ [ AS ] <correlation name>
                    [ <left paren> <derived column list> <right paren> ] ]
              | <derived table> [ AS ] <correlation name>
                    [ <left paren> <derived column list> <right paren> ]
              | <joined table>

         <derived table> ::= <table subquery>

Note that the brackets show that a <correlation name> (ie, an alias)
is optional for a regular table, but not for a subquery.

			regards, tom lane