Re: query results

Thanks Art and "Whatever...", for your comments... I'm aware of LEFT OUTER JOIN in IDS 9.3 and 9.4 (althoug it would be great if FULL OUTER join exists... but that's another story). But there is something funny... I thought that the left outer join with null filters were not fixed on 9.3 and 9.4... I tryed the approach "whatever" shows some months ago but I only get nulls on the right table... ie: ... from a left outer join b on (a.x = b.x) where b.y is null ... I also tryed ... from a left outer join b on (a.x = b.x and b.y is null) where b.x is null ... Maybe I do something wrong... I'll try with "wahtever" notes.... Art S. Kagel wrote: > On Sun, 16 Nov 2003 05:54:29 -0500, Jean Sagi wrote: > > > >>Art S. Kagel wrote: >> >> >>>... "EXISTS sub-query" is a correlated sub-query which is always slower than >>>a join and can "always [can] be converted into a join"... >> >>EXISTS sub-query always [can] be converted into a join... I can imgine how to >>do it. >> >>But >> >>Can, NOT EXISTS sub-query, be converted into a join? >> >>If so, how? (I can use this...) >> > > WHATEVER has nailed the answer, except that IDS supports LEFT OUTER joins not > RIGHT ones and it does not support sub-query-instead-of-table in the FROM > clause. As is stated in that message you use ANSI-92 syntax for a LEFT OUTER > JOIN with the join conditions in the ON clause and a filter for a NULL value in > some NOT NULL column in the dependent table (as WHATEVER implies one of the > JOIN columns is an excellent candidate for the filter. > > Art S. Kagel > >>Chucho! >> > > > -- Atte, Jes's Antonio Santos Giraldo jeansagi@myrealbox.com jeansagi@netscape.net sending to informix-list