mysql ON DELETE CASCADE

Question

网络表

"CREATE TABLE network("
 . "n_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,"
 . "nname VARCHAR(50) NOT NULL,"
 . "ndate DATE NOT NULL"
 . ");";

位置表

"CREATE TABLE locality("
 ."l_id int NOT NULL AUTO_INCREMENT PRIMARY KEY,"
 ."lname varchar(50) NOT NULL,"
 ."ldate varchar(50) NOT NULL,"
 ."n_id int NOT NULL,"
 . "CONSTRAINT locality_fk_1 FOREIGN KEY (n_id) REFERENCES network(n_id)ON DELETE CASCADE ON UPDATE CASCADE"
 . ");"; 

从评论中添加：

它给我一个以下错误：

  

网络未删除无法删除或更新父行：外键约束失败（accelore.locality，CONSTRAINT locality_ibfk_1 FOREIGN KEY（n_id）REFERENCES network（n_id））

Answer 1

您添加了外键约束，因此不会直接删除，您必须先删除约束  alter table locality drop constraint locality_ibfk_1将删除约束，您可以删除网络或
如果您只想删除表中的数据，请使用：

delete from network where n_id = n_id; 

将删除表中的所有数据而不删除任何表。或
如果您使用特定的n_id，则delete表中的特定数据。