我有两个数据表,就像这里展示的一样:
DROP TABLE IF EXISTS schemas.book;
DROP TABLE IF EXISTS schemas.category;
DROP SCHEMA IF EXISTS schemas;
CREATE SCHEMA schemas;
CREATE TABLE schemas.category (
id BIGSERIAL PRIMARY KEY,
name VARCHAR NOT NULL,
UNIQUE(name)
);
CREATE TABLE schemas.book (
id BIGSERIAL PRIMARY KEY,
published DATE NOT NULL,
category_id BIGINT NOT NULL REFERENCES schemas.category
ON DELETE CASCADE
ON UPDATE CASCADE,
author VARCHAR NOT NULL,
name VARCHAR NOT NULL,
UNIQUE(published, author, name),
FOREIGN KEY(category_id) REFERENCES schemas.category (id)
);
所以逻辑很简单,当用户删除类别x下的所有书籍后,x将从cats中删除,我尝试了上面的方法但没有成功,在我清除book表之后,category表仍然有内容,出了什么问题?