删除键 删除外键 增加外键 增加键 有大用

alter table drop key "AAA" 

alter table drop foreign key "AAA" 

ALTER TABLE `erji_user`

  ADD PRIMARY KEY (`erji_id`,`user_id`),

  ADD KEY `erji_user_user_id_foreign` (`user_id`);

--

-- 限制导出的表

--

--

-- 限制表 `erji_user`

--

ALTER TABLE `erji_user`

  ADD CONSTRAINT `erji_user_erji_id_foreign` 

  FOREIGN KEY (`erji_id`) REFERENCES `erjis` (`erji_id`) ON DELETE CASCADE;

COMMIT;