MYSQL 无法更新 parent table - 关系数据库设计、外键约束和级联更新/删除

Question

我有一个用于管理电视节目的非常简单的数据库设计：

Parenttable：tv_shows。主键：show_id
Childtable：seasons。主键：season_id，外键：show_id
Childtable：episodes。主键：episode_id，外键：season_id

Table 创作 SQL:

     $sql = "DROP TABLE IF EXISTS ".$table_shows.";
        CREATE TABLE $table_shows (
          show_id int(11) NOT NULL,
          name varchar(120) DEFAULT NULL,
          PRIMARY KEY  (show_id),
          UNIQUE KEY  show_id_UNIQUE (show_id)
        ) $charset_collate;

        DROP TABLE IF EXISTS ".$table_seasons.";
        CREATE TABLE $table_seasons (
          season_id int(10) NOT NULL,
          show_id int(11) DEFAULT NULL,
          name varchar(120) DEFAULT NULL,
          PRIMARY KEY  (season_id),
          KEY seasons_ibfk_1 (show_id),
          CONSTRAINT  seasons_ibfk_1 FOREIGN KEY  (show_id) REFERENCES $table_shows (show_id) ON DELETE CASCADE ON UPDATE CASCADE
        ) $charset_collate;

        DROP TABLE IF EXISTS ".$table_episodes.";
        CREATE TABLE $table_episodes (
          episode_id int(10) NOT NULL,
          season_id int(10) DEFAULT NULL,
          name varchar(120) DEFAULT NULL,
          PRIMARY KEY  (episode_id),
          KEY  season_id (season_id),
          CONSTRAINT  episodes_ibfk_1 FOREIGN KEY  (season_id) REFERENCES $table_seasons (season_id)
        ) $charset_collate;";

我想要发生的是，如果从 tv_shows table 中删除了一个节目，那么删除级联，因此 seasons 和 episodes 也被删除来自他们各自的 tables。

我可以很好地插入这些 table。但是，如果我尝试从 tv_shows table 中删除一行，则会收到 SQL 错误：

ERROR 1451: 1451: Cannot delete or update a parent row: a foreign key constraint fails

那么我的 FK 约束哪里出了问题？

Answer 1

您还需要将 ON DELETE CASCADE 添加到剧集中。这样可以确保它们都相互跟随进入垃圾箱。

CONSTRAINT  episodes_ibfk_1 
    FOREIGN KEY  (season_id) 
    REFERENCES $table_seasons (season_id)   
    ON DELETE CASCADE

MYSQL 无法更新 parent table - 关系数据库设计、外键约束和级联更新/删除

MYSQL Unable to update parent table - Relational Database Design, foreign key constraints and cascading update / delete

php

mysql

foreign-keys

relational-database