Re: CHECK constraint

Just a final comment...

You return a 'bool' from your funtion by virtue that the one and only
value found is a 'bool'??

If the query retures no, more than one, or a mixture of 'true' and
'false' the result might be unpredictable...  If I understand the syntax.

Would it be safer to use:

CREATE OR REPLACE FUNCTION check_bar(int4) RETURNS bigint AS'
   SELECT count(*) FROM bar WHERE id = $1 AND live = 't'
' language 'sql' STABLE STRICT;

CREATE TABLE foo (
   id int4 NOT NULL CHECK (check_bar(id) != 0)
);

???

Ben


Joe Conway wrote:
> Ben Clewett wrote:
>
>> Is this possible??  Should I cut-and-run here and do the coding in
>> application space?
>
>
> How 'bout:
>
> CREATE TABLE bar (
>   id int4 NOT NULL,
>   live bool
> );
>
> insert into bar values(1,'t');
> insert into bar values(2,'f');
>
> CREATE OR REPLACE FUNCTION check_bar(int4) RETURNS bool AS'
>   SELECT live FROM bar WHERE id = $1
> ' language 'sql' STABLE STRICT;
>
> CREATE TABLE foo (
>   id int4 NOT NULL CHECK (check_bar(id))
> );
>
> regression=# insert into foo values(1);
> INSERT 1336840 1
> regression=# insert into foo values(2);
> ERROR:  ExecInsert: rejected due to CHECK constraint "foo_id" on "foo"
>
> HTH,
>
> Joe
>
>
>
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