select * from mysql.user\G

*************************** 5. row ***************************
                    Host: localhost
                    User: root
             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
                ssl_type:
              ssl_cipher:
             x509_issuer:
            x509_subject:
           max_questions: 0
             max_updates: 0
         max_connections: 0
    max_user_connections: 0
                  plugin: mysql_native_password
   authentication_string: *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9
        password_expired: N
   password_last_changed: 2020-02-05 22:46:27
       password_lifetime: NULL
          account_locked: N
        Create_role_priv: Y
          Drop_role_priv: Y
  Password_reuse_history: NULL
     Password_reuse_time: NULL
Password_require_current: NULL
         User_attributes: NULL

主機(jī)名和用戶名共同組成復(fù)合主鍵
Host 主機(jī)名,允許訪問的客戶端，*代表所有客戶端都可以訪問
User 用戶名

create user 用戶 identified by 明文密碼
-- 用戶 用戶名@主機(jī)地址
-- 主機(jī)地址： '' 或者 %

create user 'user1'@'%' identified by '123456';
-- 查看mysql.user表中是否存在新用戶
select user, host from mysql.user where user = 'user1';
+-------+------+
| user  | host |
+-------+------+
| user1 | %    |
+-------+------+

create user user2;

drop user 用戶名@host;

mysql> drop user 'user1'@'%';
Query OK, 0 rows affected (0.01 sec)
mysql> select user, host from mysql.user where user = 'user1';
Empty set (0.00 sec)

set password for 用戶 = password(明文密碼);
set password for 'user1'@'%' = password(654321);
-- mysql5.7后續(xù)版本，8.0可用
alter user 'user1'@'%' identified by '654321';

update mysql.user set password = password(明文密碼) where user = '' and host = '';
update mysql.user set password = password('123456') where user = 'user1' and host = '%';
-- 8.0報(bào)錯(cuò)
update mysql.user set authentication_string = password('123456') where user = 'user1' and host = '%';

grant 權(quán)限列表 on 數(shù)據(jù)庫(kù)/*.表名/* to 用戶

-- 分配權(quán)限 不需要刷新，馬上生效
grant select on mydatabase.my_student to 'user1'@'%';

revoke 權(quán)限列表 /all privileges on 數(shù)據(jù)庫(kù)/*.表/* from 用戶

-- 回收權(quán)限，不需要刷新，馬上生效
revoke all privileges on mydatabase.my_student from 'user1'@'%';

flush privileges;

# 停止服務(wù)
mysql.server stop;

# 停止不了可以直接殺死進(jìn)程
ps aux|grep mysql
kill <pid>

# 重新啟動(dòng)服務(wù),跳過權(quán)限
mysqld --skip-grant-tables

# 直接無用戶名登錄
mysql

alter user 'root'@'localhost' identified by '123456';