On Wed, Aug 17, 2005 at 12:54:50PM -0400, Lane Van Ingen wrote: > Given three tables: a, b, c ; each consist of a 'keyfld' and a field called > 'foo': > tbl a tbl b tbl c > --------- --------- --------- > a.keyfld b.keyfld c.keyfld > a.foo1 b.foo2 c.foo3 > > I want to always return all of tbl a; and I want to return b.foo2 and c.foo3 > if > they can be joined to based on keyfld.a; I know that it will involve a LEFT > OUTER > JOIN on table a, but have not seen any examples of joins like this on 3 or > more > tables. > > select a.keyfld, a.foo1, b.foo2, c.foo3 > from a, b, c > where a.keyfld = <some value> > and a.keyfld = b.keyfld > and a.keyfld = c.keyfld; > > Results could look like this: > a.keyfld a.foo1 b.foo2 c.foo3 > xxxx xxxx xxxx (null) > xxxx xxxx (null) xxxx > xxxx xxxx (null) (null) > xxxx xxxx xxxx xxxx
Just use two left joins: select a.keyfld, a.foo1, b.foo2, c.foo3 from a left join b on a.keyfld = b.keyfld left join c on a.keyfld = c.keyfld where a.keyfld = <some value>; HTH, Jeremy ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
