On Sat, Dec 23, 2017 at 12:49 PM, Ken Tanzer <[email protected]> wrote:
>
>> I don't think you understand how Foreign Key constraints work in
>> PostgreSQL.
>> PostgreSQL will prevent any insert where the value of a column is not
>> within the FK table.
>> So you DO NOT need a check constraint or trigger.
>>
>>
> I thought the OP was asking for this feature ("Support for Array ELEMENT
> Foreign Keys"):
>
> https://www.postgresql.org/message-id/flat/1343842863.
> [email protected]#1343842863.5162.4.
> [email protected]
>
> which would be super-handy, but doesn't actually exist. You can enforce
> it yourself with a trigger on both tables, but I still hope this someday
> gets included into Postgres!
>
> Ken
>
>
Actually, I think the op may be referring to a MULTI COLUMN FK array
EG:
DROP TABLE drivers
CREATE TABLE drivers (
driver_id integer PRIMARY KEY,
driver_first_name text,
driver_last_name text,
CONSTRAINT drivers_uq UNIQUE (driver_first_name, driver_last_name)
);
CREATE TABLE races (
race_id integer PRIMARY KEY,
title text,
race_day DATE,
driver_first_name text,
driver_last_name text,
final_positions integer,
CONSTRAINT races_driver_fk FOREIGN KEY (driver_first_name,
driver_last_name)
REFERENCES drivers (driver_first_name, driver_last_name)
);
and that is available,
which is why I requested clarification.
So I guess we will have to wait for the op's response.
--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.
