本文操作环境：windows7系统，mysql5.5版，dell g3电脑。
mysql user表没有了怎么办？
mysql 忘记密码，重置密码，mysql.user表为空的解决办法：
一、用户表有用户，直接修改密码error 1045 (28000): access denied for user 'root'@'localhost' (using password: yes)
修改mysql配置文件my.cnf：
vim /etc/my.cnf
在[mysqld]中添加
skip-grant-tables
重启mysql服务，用空密码直接登录，查询用户表，有结果则按如下步骤修改，结果为空直接最后的解决办法
mysql> select host,user,authentication_string from mysql.user;+-----------+---------------+-------------------------------------------+| host | user | authentication_string |+-----------+---------------+-------------------------------------------+| localhost | root | *6a7a490fb9dc8c33c2b025a91737077a7e9cc5e5 || localhost | mysql.session | *thisisnotavalidpasswordthatcanbeusedhere || localhost | mysql.sys | *thisisnotavalidpasswordthatcanbeusedhere || % | root | *6a7a490fb9dc8c33c2b025a91737077a7e9cc5e5 |+-----------+---------------+-------------------------------------------+4 rows in set (0.00 sec)
修改对应用户的密码
# 重置密码为 123456mysql> update mysql.user set authentication_string=password('123456') where user='root' query ok, 2 rows affected, 1 warning (0.00 sec)rows matched: 2 changed: 2 warnings: 1# 刷新权限，使配置生效mysql> flush privileges;query ok, 0 rows affected (0.00 sec)# 退出mysql> quitbye
取消或注释掉my.cnf配置文件添加的选项 skip-grant-tables ，重启mysql服务，搞定收工。
二、用户表没有数据，则需要插入用户数据mysql> select host,user,authentication_string from mysql.user;empty set (0.00 sec)# 退出登陆mysql> exitbye
编辑my.cnf配置文件，添加或修改下面两项（我这没有sql_mode项）：
sql_mode=no_engine_substitutionskip-grant-tables
停止mysql服务，启动数据库的安全模式：mysqld_safe &使用root 空密码连接数据库： mysql -uroot -p插入root用户数据
mysql> insert into mysql.user(host,user,authentication_string) values(%,root,password(123456)); query ok, 1 row affected, 4 warnings (0.00 sec)
再次查询mysql.user表，会报错
mysql> select host,user,authentication_string from mysql.user;error 1194 (hy000): table 'user' is marked as crashed and should be repaired
需要修复mysql.user表
mysql> repair table mysql.user;+------------+--------+----------+-------------------------------------------------+| table | op | msg_type | msg_text |+------------+--------+----------+-------------------------------------------------+| mysql.user | repair | info | wrong bytesec: 113-108- 95 at 396; skipped || mysql.user | repair | info | found block that points outside data file at 32 || mysql.user | repair | info | found block that points outside data file at 36 || mysql.user | repair | info | found block that points outside data file at 40 || mysql.user | repair | info | found block that points outside data file at 44 || mysql.user | repair | info | found block that points outside data file at 48 || mysql.user | repair | info | found block that points outside data file at 52 || mysql.user | repair | info | found block that points outside data file at 56 || mysql.user | repair | info | found block that points outside data file at 60 || mysql.user | repair | warning | number of rows changed from 4 to 3 || mysql.user | repair | status | ok |+------------+--------+----------+-------------------------------------------------+11 rows in set (0.64 sec)# 再次查询user表mysql> select host,user,authentication_string from mysql.user;+-----------+---------------+-------------------------------------------+| host | user | authentication_string |+-----------+---------------+-------------------------------------------+| localhost | mysql.session | *thisisnotavalidpasswordthatcanbeusedhere || localhost | mysql.sys | *thisisnotavalidpasswordthatcanbeusedhere || % | root | *6bb4837eb74329105ee4568dda7dc67ed2ca2ad9 |+-----------+---------------+-------------------------------------------+3 rows in set (0.00 sec)
修改root用户的权限：
update mysql.user set `select_priv` = 'y', `insert_priv` = 'y', `update_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', `alter_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', `event_priv` = 'y', `trigger_priv` = 'y', `create_tablespace_priv` = 'y' where user='root';# 更新权限mysql> flush privileges;query ok, 0 rows affected (0.00 sec)# 退出登陆mysql> exitbye
退出mysql，将my.cnf配置文件的修改恢复结束mysqld_safe 进程：pkill mysql启动mysql服务: systemctl start mysql
问题解决！
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以上就是mysql user表没有了怎么办的详细内容。