Re: help with "delete joins"

On Mon, 2003-06-30 at 20:35, Josh Berkus wrote:
> Robert,
>
> > delete * from foo where not (foo.a = bar.a and foo.b=bar.b and
> > foo.c=bar.c) ;
> >
> > so i end up with
> >
> > postgres=# select * from foo;
> > a | b | c | d
> > ---+---+---+---
> > 1 | 2 | 4 | A
> > 4 | 5 | 6 | b
> > (2 rows)
> >
> > but thats not valid sql, is there some way to accomplish this?
>
> Um, your example result doesn't match your pseudo-query.

the end of a long day that started with 4 hours of sleep... no wonder I
couldn't get my head around this one. I actually did want the results of
the psuedo query, not the results I posted :-\

> Assuming that you
> want to delete everything that DOES match, not everything that DOESN'T, do:
>
> DELETE FROM foo
> WHERE EXISTS ( SELECT bar.a FROM bar
> WHERE bar.a = foo.a AND bar.b = foo.b
> AND bar.c = foo.c );

I was almost there with my original query... a NOT on your/stephan's
query gets me what I really want. :-) Thanks guys.

Robert Treat
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