mysql user表没有了的解决办法：1、在“[mysqld]”中添加“skip-grant-tables”；2、编辑my.cnf配置文件，添加“sql_mode=NO_ENGINE_SUBSTITUTION”；3、重启mysql服务。

本文操作环境：Windows7系统，mysql5.5版，Dell G3电脑。

mysql 忘记密码，重置密码，mysql.user表为空的解决办法：

ERROR1045(28000):Accessdeniedforuser'root'@'localhost'(usingpassword: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>selectHost,User,authentication_stringfrommysql.user;+-----------+---------------+-------------------------------------------+|Host|User|authentication_string|+-----------+---------------+-------------------------------------------+|localhost|root|*6A7A490FB9DC8C33C2B025A91737077A7E9CC5E5||localhost|mysql.session|*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE||localhost|mysql.sys|*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE||%|root|*6A7A490FB9DC8C33C2B025A91737077A7E9CC5E5|+-----------+---------------+-------------------------------------------+4rowsinset(0.00sec)

修改对应用户的密码

#重置密码为123456mysql>updatemysql.usersetauthentication_string=password('123456')whereuser='root'QueryOK,2rowsaffected,1warning(0.00sec)Rowsmatched:2Changed:2Warnings:1#刷新权限，使配置生效mysql>FLUSHPRIVILEGES;QueryOK,0rowsaffected(0.00sec)#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。

mysql>selectHost,User,authentication_stringfrommysql.user;Emptyset(0.00sec)#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>insertintomysql.user(Host,User,authentication_string)values("%","root",password("123456"));QueryOK,1rowaffected,4warnings(0.00sec)

再次查询mysql.user表，会报错

mysql>selectHost,User,authentication_stringfrommysql.user;ERROR1194(HY000):Table'user'ismarkedascrashedandshouldberepaired

需要修复mysql.user表

mysql>REPAIRTABLEmysql.user;+------------+--------+----------+-------------------------------------------------+|Table|Op|Msg_type|Msg_text|+------------+--------+----------+-------------------------------------------------+|mysql.user|repair|info|Wrongbytesec:113-108-95at396;Skipped||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat32||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat36||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat40||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat44||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat48||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat52||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat56||mysql.user|repair|info|Foundblockthatpointsoutsidedatafileat60||mysql.user|repair|warning|Numberofrowschangedfrom4to3||mysql.user|repair|status|OK|+------------+--------+----------+-------------------------------------------------+11rowsinset(0.64sec)#再次查询user表mysql>selectHost,User,authentication_stringfrommysql.user;+-----------+---------------+-------------------------------------------+|Host|User|authentication_string|+-----------+---------------+-------------------------------------------+|localhost|mysql.session|*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE||localhost|mysql.sys|*THISISNOTAVALIDPASSWORDTHATCANBEUSEDHERE||%|root|*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9|+-----------+---------------+-------------------------------------------+3rowsinset(0.00sec)

修改root用户的权限：

updatemysql.userset`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'whereuser='root';#更新权限mysql>flushprivileges;QueryOK,0rowsaffected(0.00sec)#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！