一, 创建用户:

命令:CREATE USER 'username'@'host' IDENTIFIED BY 'password';

说明:username - 你将创建的用户名, host - 指定该用户在哪个主机上可以登陆,如果是本地用户可用localhost, 如果想让该用户可以从任意远程主机登陆,可以使用通配符%. password - 该用户的登陆密码,密码可以为空,如果为空则该用户可以不需要密码登陆服务器.

例子:

CREATE USER `root`@`localhost` IDENTIFIED BY `123456` ;    //指定IP,指定密码123456
CREATE USER 'pig'@'192.168.1.101_' IDENDIFIED BY '123456';   //指定IP,指定密码123456
CREATE USER 'pig'@'%' IDENTIFIED BY '123456';   //不限IP,指定密码123456
CREATE USER 'pig'@'%' IDENTIFIED BY '';  //不限IP,空密码
CREATE USER 'pig'@'%';    //不限IP,空密码

二,授权:

命令:GRANT privileges ON databasename.tablename TO ‘username’@‘host’

> mysql>  grant all privileges on *.* to 'yangxin'@'%' identified by 'yangxin123456' with grant option;

all privileges：表示将所有权限授予给用户。也可指定具体的权限，如：SELECT、CREATE、DROP等。
on：表示这些权限对哪些数据库和表生效，格式：数据库名.表名，这里写“*”表示所有数据库，所有表。如果我要指定将权限应用到test库的user表中，可以这么写：test.user
to：将权限授予哪个用户。格式：”用户名”@”登录IP或域名”。%表示没有限制，在任何主机都可以登录。比如：”yangxin”@”192.168.0.%”，表示yangxin这个用户只能在192.168.0 IP段登录
identified by：指定用户的登录密码
with grant option：表示允许用户将自己的权限授权给其它用户
可以使用GRANT给用户添加权限，权限会自动叠加，不会覆盖之前授予的权限，比如你先给用户添加一个SELECT权限，后来又给用户添加了一个INSERT权限，那么该用户就同时拥有了SELECT和INSERT权限。

例子:

GRANT ALL ON *.* TO 'pig'@'%'; 
GRANT ALL privileges ON hichat.* TO 'hichat'@'127.0.0.1'; 
GRANT ALL privileges ON *.* TO 'root'@'127.0.0.1' with grant option;  //最高权限，授权功能
flush privileges;  //刷新授权

注意:用以上命令授权的用户不能给其它用户授权,如果想让该用户可以授权,用以下命令:

GRANT privileges ON databasename.tablename TO 'username'@'host' WITH GRANT OPTION; 

三.设置与更改用户密码:

命令:SET PASSWORD FOR 'username'@'host' = PASSWORD('newpassword');如果是当前登陆用户用SET PASSWORD = PASSWORD("newpassword");

例子: SET PASSWORD FOR 'pig'@'%' = PASSWORD("123456");

四.撤销用户权限:

命令: REVOKE privilege ON databasename.tablename FROM 'username'@'host';

说明: privilege, databasename, tablename - 同授权部分.

例子: REVOKE SELECT ON *.* FROM 'pig'@'%';

注意: 假如你在给用户’pig’@’%'授权的时候是这样的(或类似的):GRANT SELECT ON test.user TO 'pig'@'%', 则在使用REVOKE SELECT ON *.* FROM 'pig'@'%';命令并不能撤销该用户对test数据库中user表的SELECT 操作.相反,如果授权使用的是GRANT SELECT ON *.* TO 'pig'@'%';则REVOKE SELECT ON test.user FROM 'pig'@'%';命令也不能撤销该用户对test数据库中user表的Select 权限.

具体信息可以用命令SHOW GRANTS FOR 'pig'@'%'; 查看.

五.删除用户:

命令: DROP USER 'username'@'host';

附表:在MySQL中的操作权限（关键字及解释）：

ALTER Allows use of ALTER TABLE.
ALTER ROUTINE Alters or drops stored routines.
CREATE Allows use of CREATE TABLE.
CREATE ROUTINE Creates stored routines.
CREATE TEMPORARY TABLE Allows use of CREATE TEMPORARY TABLE.
CREATE USER Allows use of CREATE USER, DROP USER, RENAME USER, and REVOKE ALL PRIVILEGES.
CREATE VIEW Allows use of CREATE VIEW.
DELETE Allows use of DELETE.
DROP Allows use of DROP TABLE.
EXECUTE Allows the user to run stored routines.
FILE Allows use of SELECT… INTO OUTFILE and LOAD DATA INFILE.
INDEX Allows use of CREATE INDEX and DROP INDEX.
INSERT Allows use of INSERT.
LOCK TABLES Allows use of LOCK TABLES on tables for which the user also has SELECT privileges.
PROCESS Allows use of SHOW FULL PROCESSLIST.
RELOAD Allows use of FLUSH.
REPLICATION Allows the user to ask where slave or master
CLIENT servers are.
REPLICATION SLAVE Needed for replication slaves.
SELECT Allows use of SELECT.
SHOW DATABASES Allows use of SHOW DATABASES.
SHOW VIEW Allows use of SHOW CREATE VIEW.
SHUTDOWN Allows use of mysqladmin shutdown.
SUPER Allows use of CHANGE MASTER, KILL, PURGE MASTER LOGS, and SET GLOBAL SQL statements. Allows mysqladmin debug command. Allows one extra connection to be made if maximum connections are reached.
UPDATE Allows use of UPDATE.
USAGE Allows connection without any specific privileges.

【飙歌实战】

1.首先要创建一个数据库

create database test_db;

2.授权某个用户拥有某个数据库的所有权限

grant all privileges on test_db.* to user_name@'%'identified by 'password';

粗体是要替换成自己的数据库、数据库用户名、数据库密码

3.修改root密码： SET PASSWORD FOR 'root'@'localhost' = PASSWORD('yourpassword');

flush privileges;