更新Postgresql 9.1数据库中的约束

Question

我想将“在删除限制时”更改为“在删除级联时”：我该怎么做？

ALTER TABLE T1
ADD CONSTRAINT fk_T1 FOREIGN KEY (id1)
  REFERENCES T2 (id1) MATCH SIMPLE
  ON UPDATE RESTRICT ON DELETE RESTRICT;

Answer 1

您必须删除它并重新创建它。

ALTER TABLE T1 DROP CONSTRAINT fk_T1;

ALTER TABLE T1 ADD CONSTRAINT fk_T1 FOREIGN KEY (id1)
REFERENCES T2 (id1) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE;