在mysql命令行中执行

SET PASSWORD FOR 'root'@'localhost' = PASSWORD('123456XXX'); 

GRANT ALL PRIVILEGES ON *.* TO 'root' @'%' IDENTIFIED BY '123456XXX' WITH GRANT OPTION;

flush privileges;

 

若以上方法行不通则用：

use mysql;  

UPDATE user SET Password=PASSWORD('123456') where USER='root';

flush privileges;