mysql create user and authorization

1. Create a user

Order:

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

illustrate:

• username: the username you will create
• host: Specify the host on which the user can log in. If it is a local user, localhost can be used. If you want the user to log in from any remote host , you can use wildcards%
• password: the user's login password, the password can be empty, if it is empty, the user does not need a password to log in to the server

example:

CREATE USER 'dog'@'localhost' IDENTIFIED BY '123456';
CREATE USER 'pig'@'192.168.1.101_' IDENDIFIED BY '123456';
CREATE USER 'pig'@'%' IDENTIFIED BY '123456';
CREATE USER 'pig'@'%' IDENTIFIED BY '';
CREATE USER 'pig'@'%';

Problems encountered: (in the environment of the Debian system, mysql 5.7)

Create a new user for testing:

mysql> create user 'fixdq'@'localhost' identfied by  '123';

Error:ERROR 1819 (HY000): Your password does not satisfy the current policy requirements。

problem causes:

Because the plugin is installed by default in MySQL 5.7 validate_password, and the password setting is simple, this error will be reported.

Above:

Order:

mysql>show plugins;

mysql> show variables like 'vali%';

After 5.7 initialization, this plugin will be installed by default. If it is not installed, it SHOW VARIABLES LIKE 'vali%'will return empty.
The value of the corresponding parameter is also the default value, the following is the explanation of these values

validate_password_length 8 #The minimum length of the password, here is 8. 
validate_password_mixed_case_count 1 #At least the number of lowercase or uppercase letters must be included, here is 1. 
validate_password_number_count 1 #At least the number of numbers to include, here is 1. 
validate_password_policy MEDIUM # Strength level, where its value can be set to 0, 1, 2. Corresponding respectively: 
【0/ LOW】: Only check the length.
【 1/ MEDIUM 】: On the basis of level 0, check more numbers, upper and lower case, and special characters.
【 2/ STRONG 】: Check the special character dictionary file on the basis of level 1, here is 1.
validate_password_special_char_count 1 #At least the number of numeric characters to be included, here is 1.

solution:

To turn off this plugin, add the following configuration to the configuration file and restart mysqld:

The default mysql 5.7 configuration file path installed by apt-get /etc/mysql/my.cnf 

Please modify the configuration file according to the path of your own installation

$ sudo vi /etc/mysql/my.cnf

[mysqld]
validate_password=off

 

Reboot:

$ sudo /etc/init.d/mysql restart
$ sudo mysql

mysql>show plugins;

mysql>show variables like 'vali%';

 

result:

mysql> create user 'fixdq'@'localhost' identfied by  '123';

Create user successfully

 

2. Authorization

Order:

GRANT privileges ON databasename.tablename TO 'username'@'host'

illustrate:

• Privileges: the user's operation privileges, such as SELECT, INSERT, UPDATEetc., if you want to grant the privileges, useALL
• databasename: database name
• tablename: table name, if you want to grant the user the corresponding operation permissions on all databases and tables, it can be *expressed, such as*.*

example:

GRANT SELECT, INSERT ON test.user TO 'pig'@'%';
GRANT ALL ON *.* TO 'pig'@'%';
GRANT ALL ON maindataplus.* TO 'pig'@'%';

Notice:

A user authorized with the above command cannot authorize other users. If you want the user to be authorized, use the following command:

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

3. Set and change user password

Order:

SET PASSWORD FOR 'username'@'host' = PASSWORD('newpassword');

example:

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

Fourth, revoke user permissions

Order:

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

PS: privilege, databasename, tablename: the same as the authorization part

example:

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

Notice:

If you 'pig'@'%'authorize the user like this (or similar): GRANT SELECT ON test.user TO 'pig'@'%', then using the REVOKE SELECT ON *.* FROM 'pig'@'%';command does not undo the user's operations on the user table in the test database SELECT. On the contrary, if the authorization is used, GRANT SELECT ON *.* TO 'pig'@'%';the REVOKE SELECT ON test.user FROM 'pig'@'%';command cannot revoke the user's authority to the user table in the test database Select.

The specific information can be viewed with the command SHOW GRANTS FOR 'pig'@'%';.

5. Delete users

Order:

DROP USER 'username'@'host';