mysql误删除root用户或者忘记root密码时的解决办法
一不小心删除了mysql的root用户，在网上找了很多办法都没有解决，由于mysql数据库比较多，重装又太麻烦，所以一直在努力尝试各种方法，最后终于成功了。步骤如下：
1、先结束mysqld进程
#killall mysqld
不加载grant_tables而进入mysql
#mysqld_safe --skip-grant-tables &
进入mysql
#/usr/local/mysql/bin/mysql
mysql> use mysql
Database changed
mysql> select * from user;
Empty set (0.00 sec)
mysql> insert into user set user='root',ssl_cipher='',x509_issuer='',x509_subject='';
(增加root用户的表）
Query OK, 1 row affected, 3 warnings (0.00 sec)
(这时可能会提示某字段如ssl_cipher无默认值, 只要加上,ssl_cipher=''; 其字段如有提示依次添加就OK了)
update
user set Host='localhost',select_priv='y',
insert_priv='y',update_priv='y',
Alter_priv='y',delete_priv='y',create_priv='y',drop_priv='y',reload_priv='y',shutdown_priv='y',Process_priv='y',file_priv='y',grant_priv='y',References_priv='y',index_priv='y',create_user_priv='y',show_db_priv='y',super_priv='y',create_tmp_table_priv='y',Lock_tables_priv='y',execute_priv='y',repl_slave_priv='y',repl_client_priv='y',create_view_priv='y',show_view_priv='y',create_routine_priv='y',alter_routine_priv='y',create_user_priv='y'
where user='root';
(这里面是修改root用户的权限)
mysql> quit;
2、带权限正常启动mysql
#service mysqld start
3、使用root用户登录（如果有phpadmin就直接用root空密码登录再修改密码或权限就可以了）
#mysql -u root -p
mysql> update user set password=password('123456') where user='root';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> flush privileges;
mysql> quit
试下没有密码时进入mysql
#mysql -u root
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
使用密码进入mysql
#mysql -u root -p 123456
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 25 to server version: 4.1.20
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql>