Re: [GENERAL] database constraints

[Dennis Gearon]

Use a post trigger function, ON UPDATE, INSERT which essentially has 
this in it:

if ( ISNULL(new.a) AND ISNULL(new.b) ){ RAISE NOTICE "blah blah"; }
I work with PHP a lot, just a little plpgsql, so, the grammar may be 
wrong above.
Ben <[EMAIL PROTECTED]> wrote:
<quote --------------------------------------------------------------->
If I have have the table:

create table foo
(
   a int references bar(id),
   b int references baz(id)
)
... how do I make sure one and only one of the columns a and b are 
non-null? Is it even reasonable?
</quote -------------------------------------------------------------->

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