Re: Checking number of entries

At 16:57 28/09/00 -0700, Alfred Perlstein wrote:
>* Wade D. Oberpriller <oberpwd(at)anubis(dot)network(dot)com> [000928 15:34] wrote:
>> Hello,
>>
>> Is it possible to restrict the number of entries in a table? I have
attempted
>> to write a check like so:
>>
>> CREATE TABLE mytable (
>> id integer NOT NULL,
>> CHECK (COUNT(id) <= 10)
>> );
>>
>> This is not allowed, I get an error saying:
>>
>> ERROR: ExecEvalAggref: no aggregates in this expression context

I just tried:

CREATE TABLE mytable (
id integer NOT NULL
);

Alter TABLE mytable Add
CHECK ( (Select COUNT(distinct id) From mytable) <= 10)
);

Under 7.1 (and with the constraint in the table definition in 7.0.2) and it
lets me define the table & constraint, but when I insert into the table, I
get:

ERROR: ExecEvalExpr: unknown expression type 108

Seems to me it should either disallow the creation, or work properly.

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