Suppose we have the usual order & order line item entities:
CREATE TABLE "order" ( id INT PRIMARY KEY, date DATE NOT NULL);
CREATE TABLE orderlineitem ( id INT PRIMARY KEY, orderid INT REFERENCES "order"(id), seq INT NOT NULL, CONSTRAINT
con1UNIQUE (orderid, seq), productid INT NOT NULL, quantity INT NOT NULL, price NUMERIC(18,4) NOT NULL);
how do we enforce things like, for example: a) each order must contain
at least 1 line item; or b) each order must have a non-zero total value;
without making INSERT painful? I'm new to triggers, so I'm thinking of
something like a "before COMMIT" trigger but there's no such thing
apparently.
Regards,
dave