On 2013-11-04 14:44, Jason Long wrote:
CREATE TABLE t_a
(
id bigint NOT NULL,
CONSTRAINT pk_a PRIMARY KEY (id)
);
CREATE TABLE t_b
(
id bigint NOT NULL,
CONSTRAINT pk_b PRIMARY KEY (id),
CONSTRAINT fk_b_a FOREIGN KEY (id) REFERENCES t_a (id) ON DELETE
CASCADE
);
INSERT INTO t_a VALUES (1),(2),(3);
INSERT INTO t_b VALUES (1),(2),(3);
delete from t_b where id = 2;
select * from t_a;
This depends entirely on your use case and how your data actually relate
to each other, but an alternative to using a trigger to do that delete
you could possibly go with inheritance and avoid the foreign keys
altogether. Presumably the other tables you mention that might have
references to t_a should also be defined as inheriting from A if they
have the same relationship to A that B does.
Example:
CREATE TABLE t_a
(
id bigint NOT NULL,
CONSTRAINT pk_a PRIMARY KEY (id)
);
CREATE TABLE t_b
(
CONSTRAINT pk_b PRIMARY KEY (id)
)
inherits (t_a);
INSERT INTO t_b VALUES (1),(2),(3);
select * from t_a;
delete from t_a where id = 2;
select * from t_a;
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