Обсуждение: JOIN syntax

Looking at SQL92, it seems that I ought to be able to do this:

SELECT * FROM invoice INNER JOIN (SELECT * FROM invoice_line WHERE lineno > 1) 
ON invoice.invno = invoice_line.invno;
ERROR:  parser: parse error at or near "("

(I know it can be successfully expressed in a more complex WHERE clause).

Is there anything wrong with the syntax, or is it a missing feature?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
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> Looking at SQL92, it seems that I ought to be able to do this:
> SELECT * FROM invoice INNER JOIN
>  (SELECT * FROM invoice_line WHERE lineno > 1)
>  ON invoice.invno = invoice_line.invno;
> ERROR:  parser: parse error at or near "("

Wrong syntax (for Postgres anyway). We don't yet have subselects in the
syntax. Thanks for the example though; it seems like some variant should
be allowed, though perhaps not as written above.

Something like
 select * from invoice inner join   (select * from invoice_line where lineno > 1)     as IL (invno, yada)   on
invoice.invno= IL.invno;
 

seems like it could be legal. Your variant of this may have trouble
hooking up invoice_line.invno after the subselect, since the subselect
result may lose the linkage with the underlying input table.

But, all this is theoretical, since Postgres doesn't yet do the right
thing at all.
                       - Thomas