錯誤代碼1833 Cannot change column used in a foreign

最近修改mysql數據庫表中的字段長度時報錯，執行更改的sql語句：
ALTER TABLE server_list MODIFY COLUMN server_lip CHAR(25);

報錯信息：
1 queries executed, 0 success, 1 errors, 0 warnings
查詢：alter table server_list modify column server_lip char(25)
錯誤代碼： 1833
Cannot change column 'server_lip': used in a foreign key constraint 'server_history_ibfk_1' of table 'OMServer.server_history'

緣由：server_list表中的server_lip字段爲server_history表的外鍵，server_history建表語句：
CREATE TABLE server_history (
ID int(11) NOT NULL AUTO_INCREMENT COMMENT '主鍵ID',
history_id int(11) NOT NULL COMMENT '事件ID',
history_ip char(15) NOT NULL COMMENT '事件IP地址',
history_user char(15) NOT NULL COMMENT '事件用戶名',
history_datetime datetime NOT NULL COMMENT '事件時間',
db_datetime timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '入庫時間',
history_command char(255) NOT NULL COMMENT '事件命令',
PRIMARY KEY (ID),
KEY history_ip (history_ip),
CONSTRAINT server_history_ibfk_1 FOREIGN KEY (history_ip) REFERENCES server_list (server_lip)
) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8 COMMENT='操做事件表'

解決步驟：
1.鎖表
LOCK TABLES server_history WRITE,server_list WRITE;
2.查看是否被鎖

3.解除server_history表外鍵約束
ALTER TABLE server_history DROP FOREIGN KEY server_history_ibfk_1;
4.更改server_list表server_lip字段長度
ALTER TABLE server_list MODIFY COLUMN server_lip CHAR(25);
查看錶結構發現已完成字段長度更新

5.新增server_history表外鍵約束
ALTER TABLE server_history ADD CONSTRAINT server_history_ibfk_1 FOREIGN KEY (history_ip) REFERENCES server_list (server_lip);
6.解除鎖定
UNLOCK TABLES;