以编程方式将ON DELETE CASCADE添加到所有表的现有外键约束中

import mysql.connector

# 连接到MySQL数据库
cnx = mysql.connector.connect(user='username', password='password', host='localhost', database='database_name')
cursor = cnx.cursor()

# 获取数据库中所有的表和外键约束信息
cursor.execute("SELECT TABLE_NAME, CONSTRAINT_NAME, REFERENCED_TABLE_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE CONSTRAINT_SCHEMA = 'database_name' AND REFERENCED_TABLE_NAME IS NOT NULL")

for (table_name, constraint_name, referenced_table_name) in cursor:
    # 检查外键约束是否已经设置了ON DELETE CASCADE选项
    cursor.execute("SELECT UPDATE_RULE FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS WHERE CONSTRAINT_SCHEMA = 'database_name' AND CONSTRAINT_NAME = %s", (constraint_name,))
    update_rule = cursor.fetchone()[0]
    
    if update_rule != 'CASCADE':
        # 修改外键约束，添加ON DELETE CASCADE选项
        alter_statement = "ALTER TABLE {} DROP FOREIGN KEY {}, ADD FOREIGN KEY {} REFERENCES {} ON DELETE CASCADE".format(table_name, constraint_name, constraint_name, referenced_table_name)
        cursor.execute(alter_statement)

# 提交修改并关闭连接
cnx.commit()
cursor.close()
cnx.close()