解决Cannot drop index '*****': needed in a foreign key constraint

今天小编在用mysql数据库去删除一个表的字段时遇到了Cannot drop index 'PK_school_province': needed in a foreign key constraint问题，如下将表的创建贴出来：

CREATE TABLE `school` (
  `school_id` int(11) NOT NULL AUTO_INCREMENT,
  `school_name` varchar(255) NOT NULL,
  `school_pro_id` int(11) NOT NULL,
  PRIMARY KEY (`school_id`),
  KEY `PK_school_province` (`school_pro_id`),
  CONSTRAINT `PK_school_province` FOREIGN KEY (`school_pro_id`) REFERENCES `province` (`province_id`)
) ENGINE=InnoDB AUTO_INCREMENT=2735 DEFAULT CHARSET=utf8

大家都知道KEY与index的意思相近，都是创建索引，现在使用coinstraint来将对字段进行限制，将索引PK_school_province 与外键school_pro_id与外表province表的province_id限制关联（constraint也有索引的意思，on面跟语句），那么现在我想直接删除school_pro_id这个字段，这时，直接使用"alter table school drop column school_pro_id"会出现Cannot drop index 'PK_school_province': needed in a foreign key constraint;大意是不能删除被外键限制的索引PK_school_province。那么这个时候我们需要将外键限制的索引给删除掉，使用”alter table school drop foreign key PK_school_province“就能将PK_school_province删除掉，那么这个时候再使用“alter table school drop column school_pro_id”就可以将school表中的school_pro_id删除掉。

https://www.cnblogs.com/hubavyn/p/4359315.html