"Poul L. Christiansen" <poulc@cs.auc.dk> writes:
> <html><head></head><body>Using the example:<br>
> SELECT '' AS "xxx", *<br>
> FROM J1_TBL LEFT OUTER JOIN J2_TBL USING (i);<br>
> <br>
> ..doesn't work because the columns which I am using to join the tables don't
> have the same name. How do i specify the columns if they don't have the same
> name?<br>
USING is just for the simple case where you want to join on identically-
named columns. (In the even simpler case where you want to join on all
identically-named columns, just say NATURAL JOIN.)
Whenever you need something more complicated, you say ON some-condition,
eg
SELECT '' AS "xxx", *
FROM J1_TBL LEFT OUTER JOIN J2_TBL ON j1_tbl.x = j2_tbl.y
Note that unlike USING and NATURAL, an ON-condition doesn't cause
columns to be omitted from the join result. So in the above example
you'd see both x and y as output columns.
> Poul L. Christiansen<br>
> <br>
> Tom Lane wrote:<br>
> <blockquote type=3D"cite" cite=3D"mid:6858.976116402@sss.pgh.pa.us"><pre wr=
> ap=3D"">"Poul L. Christiansen" <a class=3D"moz-txt-link-rfc2396E" href=3D"m=
> ailto:poulc@cs.auc.dk"><poulc@cs.auc.dk></a> writes:<br></pre>
> <blockquote type=3D"cite"><pre wrap=3D"">But how do I make an outer join?=
> <br>What's the syntax?<br>I will RTFM if someone points me to the docs :-)=
> <br></pre></blockquote>
> <pre wrap=3D""><!----><br>I'm afraid I haven't updated the FM yet :-( .=
> .. but you could look at<br>the examples in the JOIN regress test, src/test=
> /regress/sql/join.sql.<br><br>Or, from the SQL92 spec, here's the grammar:<=
br> <br> <from clause> ::=3D FROM <table reference> [ { =
> <comma> <table reference> }... ]<br><br> <table refe=
> rence> ::=3D<br> <table name> [ [ AS ] <correlat=
> ion name><br> [ <left paren> <derived column=
> list> <right paren> ] ]<br> | <derived table> =
> [ AS ] <correlation name><br> [ <left paren>=
> <derived column list> <right paren> ]<br> | <j=
> oined table><br><br> <derived table> ::=3D <table subqu=
> ery><br><br> <derived column list> ::=3D <column name l=
> ist><br><br> <column name list> ::=3D<br> <=
> ;column name> [ { <comma> <column name> }...
> </blockquote>
> <br>
> </body></html>
BTW, would you PLEASE turn off the HTML option in your mail program?
regards, tom lane