-- 如果host值不是%， 就要加上host值,下面查看bkpuser用户权限(6个权限, 限本地连接)
SHOW GRANTS FOR bkpuser@localhost;

-- 如果host值是%, 就只要输入用户名,下面查看z1用户权限(显示所有权限，不限ip连接)
SHOW GRANTS FOR z1;

-- 例1:
CREATE USER 'z2'@'localhost' IDENTIFIED BY '123456';
-- 赋给z2@localhost用户在所有数据库上的所有表的select 权限
GRANT SELECT ON *.* TO 'z2'@'localhost' 
-- 查看权限
    SHOW GRANTS FOR z2@localhost;

--例2: 使用grant 来新增权限,新增一个insert权限，并和已有的select 权限进行合并
GRANT SELECT,INSERT ON *.* TO 'z2'@'localhost'

--例3: 使用revoke语句可以回收已经赋予的权限
  -- 语法如下：
REVOKE
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    FROM user [, user] ...

-- 回收insert权限，注意像usage登录权限是不能回收的。因为revoke并不能删除用户
REVOKE INSERT ON *.* FROM  'z2'@'localhost';

 --  (1)使用mysqladmin来修改，如果host是%,则-h 的host为空
 [root@hsr ~]# mysqladmin -u z1 -h ''  password '123456' -p
Enter password: 
mysqladmin: [Warning] Using a password on the command line interface can be insecure.
Warning: Since password will be sent to server in plain text, use ssl connection to ensure password safety.

-- (2) set password 
SET PASSWORD FOR 'z1'@'%'=PASSWORD('654321')
Warning Code : 1287
'SET PASSWORD FOR <user> = PASSWORD('<plaintext_password>')' is deprecated and will be removed in a future release. 
Please use SET PASSWORD FOR <user> = '<plaintext_password>' instead

-- (3) 使用grant来修改密码
GRANT USAGE  ON *.* TO 'z1'@'%' IDENTIFIED BY '123456'
Using GRANT statement to modify existing user's properties other than privileges is deprecated and will be removed in future release.
 Use ALTER USER statement for this operation.

--(4) 修改 user表
UPDATE mysql.`user` SET   authentication_string=PASSWORD('654321') WHERE `Host`='%' AND `User`='z1'
Warning Code : 1681
'PASSWORD' is deprecated and will be removed in a future release.
-- 记住要刷新才生效。
FLUSH PRIVILEGES

--例如删除z2用户
DROP USER  'z2'@'localhost'
-- 查看权限
SHOW GRANTS FOR z2@localhost;