深圳平面广告设计公司_邢台瑞光网络科技有限公司_电子商务网站建设的步骤_网络推广方法有哪几种

1.查看所有约束

SELECT CONSTRAINT_NAME, TABLE_NAME, CONSTRAINT_TYPE 
FROM information_schema.TABLE_CONSTRAINTS 
WHERE TABLE_NAME = '表名字';

2.删除约束

ALTER TABLE bus_qualification DROP INDEX unique_item_name;

3.添加约束

ALTER TABLE bus_qualification ADD UNIQUE KEY unique_item_name_company (item_name, item_company);

4.查看具体约束

SELECT COLUMN_NAME, CONSTRAINT_NAME 
FROM information_schema.KEY_COLUMN_USAGE 
WHERE TABLE_NAME = '表名';