From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Joost Kraaijeveld" <J(dot)Kraaijeveld(at)Askesis(dot)nl> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: alias required by standard or PostgreSQL? |
Date: | 2007-12-03 06:13:29 |
Message-ID: | 9788.1196662409@sss.pgh.pa.us |
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Lists: | pgsql-sql |
"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
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