Re: " ::= " grammar rule not accepted by Postgres

On 06/15/2011 10:59 PM, Tom Lane wrote:
> Clem Dickey<dickeycl@us.ibm.com>  writes:
>> This expression is (I think) a well-formed query, but is rejected by
>> Postgresql 8.4 (t is a table name).
>
>>    t t1 NATURAL JOIN t t2;
>
> Hmm ... I think you are looking at SQL92 or SQL99.

> [ digs a bit more... ]  Ah, here we are: Annex E of SQL:2003 calls out
> various incompatibilities from SQL:99, notably
>
>     6) In ISO/IEC 9075-2:1999, a<query expression body>,<query
>     term>, or<query primary>  could consist of a<joined
>     table>. None of those three elements can consist of a<joined
>     table>  in this edition of ISO/IEC 9075.

Thanks for the research. I was indeed reading from SQL99, which was 
current the last time I used SQL. I'll have to spring for a newer 
standard (or the equivalent).