mysql修改root密码
修改root密码命令如下，dos下登录mysql：
命令:mysql> use mysql

Database changed

mysql> update user set password=PASSWORD('123456') where user='root';

Query OK, 0 rows affected (0.00 sec)

Rows matched: 1 Changed: 0 Warnings: 0

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

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不要忘记重启mysql?