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5.5.2. Adding User Accounts

You can create MySQL accounts in two ways:

  • By using statements intended for creating accounts, such as CREATE USER or GRANT. These statements cause the server to make appropriate modifications to the grant tables.

  • By manipulating the MySQL grant tables directly with statements such as INSERT, UPDATE, or DELETE.

The preferred method is to use account-creation statements because they are more concise and less error-prone than manipulating the grant tables directly. CREATE USER and GRANT are described in Section 12.4.1, “Account Management Statements”.

Another option for creating accounts is to use one of several available third-party programs that offer capabilities for MySQL account administration. phpMyAdmin is one such program.

The following examples show how to use the mysql client program to set up new accounts. These examples assume that privileges have been set up according to the defaults described in Section 2.17.3, “Securing the Initial MySQL Accounts”. This means that to make changes, you must connect to the MySQL server as the MySQL root user, and the root account must have the INSERT privilege for the mysql database and the RELOAD administrative privilege.

As noted in the examples where appropriate, some of the statements will fail if the server's SQL mode has been set to enable certain restrictions. In particular, strict mode (STRICT_TRANS_TABLES, STRICT_ALL_TABLES) and NO_AUTO_CREATE_USER will prevent the server from accepting some of the statements. Workarounds are indicated for these cases. For more information about SQL modes and their effect on grant table manipulation, see Section 5.1.7, “Server SQL Modes”, and Section 12.4.1.3, “GRANT Syntax”.

First, use the mysql program to connect to the server as the MySQL root user: 

shell> mysql --user=root mysql

If you have assigned a password to the root account, you'll also need to supply a --password or -p option, both for this mysql command and for those later in this section.

After connecting to the server as root, you can add new accounts. The following statements use GRANT to set up four new accounts: 

mysql> CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'
    ->     WITH GRANT OPTION;
mysql> CREATE USER 'monty'@'%' IDENTIFIED BY 'some_pass';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'%'
    ->     WITH GRANT OPTION;
mysql> CREATE USER 'admin'@'localhost';
mysql> GRANT RELOAD,PROCESS ON *.* TO 'admin'@'localhost';
mysql> CREATE USER 'dummy'@'localhost';

The accounts created by these statements have the following properties:

  • Two of the accounts have a user name of monty and a password of some_pass. Both accounts are superuser accounts with full privileges to do anything. The 'monty'@'localhost' account can be used only when connecting from the local host. The 'monty'@'%' account uses the '%' wildcard for the host part, so it can be used to connect from any host.

    It is necessary to have both accounts for monty to be able to connect from anywhere as monty. Without the localhost account, the anonymous-user account for localhost that is created by mysql_install_db would take precedence when monty connects from the local host. As a result, monty would be treated as an anonymous user. The reason for this is that the anonymous-user account has a more specific Host column value than the 'monty'@'%' account and thus comes earlier in the user table sort order. (user table sorting is discussed in Section 5.4.4, “Access Control, Stage 1: Connection Verification”.)

  • The 'admin'@'localhost' account has no password. This account can be used only by admin to connect from the local host. It is granted the RELOAD and PROCESS administrative privileges. These privileges allow the admin user to execute the mysqladmin reload, mysqladmin refresh, and mysqladmin flush-xxx commands, as well as mysqladmin processlist . No privileges are granted for accessing any databases. You could add such privileges later by issuing additional GRANT statements.

  • The 'dummy'@'localhost' account has no password. This account can be used only to connect from the local host. No privileges are granted. It is assumed that you will grant specific privileges to the account later.

The statements that create accounts with no password will fail if the NO_AUTO_CREATE_USER SQL mode is enabled. To deal with this, use an IDENTIFIED BY clause that specifies a nonempty password.

To check the privileges for an account, use SHOW GRANTS: 

mysql> SHOW GRANTS FOR 'admin'@'localhost';
+-----------------------------------------------------+
| Grants for admin@localhost                          |
+-----------------------------------------------------+
| GRANT RELOAD, PROCESS ON *.* TO 'admin'@'localhost' |
+-----------------------------------------------------+

As an alternative to CREATE USER and GRANT, you can create the same accounts directly by issuing INSERT statements and then telling the server to reload the grant tables using FLUSH PRIVILEGES: 

shell> mysql --user=root mysql
mysql> INSERT INTO user
    ->     VALUES('localhost','monty',PASSWORD('some_pass'),
    ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y');
mysql> INSERT INTO user
    ->     VALUES('%','monty',PASSWORD('some_pass'),
    ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
    ->     'Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y','Y',
    ->     '','','','',0,0,0,0);
mysql> INSERT INTO user SET Host='localhost',User='admin',
    ->     Reload_priv='Y', Process_priv='Y';
mysql> INSERT INTO user (Host,User,Password)
    ->     VALUES('localhost','dummy','');
mysql> FLUSH PRIVILEGES;

When you create accounts with INSERT, it is necessary to use FLUSH PRIVILEGES to tell the server to reload the grant tables. Otherwise, the changes go unnoticed until you restart the server. With CREATE USER, FLUSH PRIVILEGES is unnecessary.

The reason for using the PASSWORD() function with INSERT is to encrypt the password. The CREATE USER statement encrypts the password for you, so PASSWORD() is unnecessary.

The 'Y' values enable privileges for the accounts. Depending on your MySQL version, you may have to use a different number of 'Y' values in the first two INSERT statements. The INSERT statement for the admin account employs the more readable extended INSERT syntax using SET.

In the INSERT statement for the dummy account, only the Host, User, and Password columns in the user table row are assigned values. None of the privilege columns are set explicitly, so MySQL assigns them all the default value of 'N'. This is equivalent to what CREATE USER does.

If strict SQL mode is enabled, all columns that have no default value must have a value specified. In this case, INSERT statements must explicitly specify values for the ssl_cipher, x509_issuer, and x509_subject columns.

To set up a superuser account, it is necessary only to create a user table entry with the privilege columns set to 'Y'. The user table privileges are global, so no entries in any of the other grant tables are needed.

The next examples create three accounts and give them access to specific databases. Each of them has a user name of custom and password of obscure.

To create the accounts with CREATE USER and GRANT, use the following statements: 

shell> mysql --user=root mysql
mysql> CREATE USER 'custom'@'localhost' IDENTIFIED BY 'obscure';
mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
    ->     ON bankaccount.*
    ->     TO 'custom'@'localhost';
mysql> CREATE USER 'custom'@'host47.example.com' IDENTIFIED BY 'obscure';
mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
    ->     ON expenses.*
    ->     TO 'custom'@'host47.example.com';
mysql> CREATE USER 'custom'@'server.domain' IDENTIFIED BY 'obscure';
mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
    ->     ON customer.*
    ->     TO 'custom'@'server.domain';

The three accounts can be used as follows:

  • The first account can access the bankaccount database, but only from the local host.

  • The second account can access the expenses database, but only from the host host47.example.com.

  • The third account can access the customer database, but only from the host server.domain.

To set up the custom accounts without GRANT, use INSERT statements as follows to modify the grant tables directly: 

shell> mysql --user=root mysql
mysql> INSERT INTO user (Host,User,Password)
    ->     VALUES('localhost','custom',PASSWORD('obscure'));
mysql> INSERT INTO user (Host,User,Password)
    ->     VALUES('host47.example.com','custom',PASSWORD('obscure'));
mysql> INSERT INTO user (Host,User,Password)
    ->     VALUES('server.domain','custom',PASSWORD('obscure'));
mysql> INSERT INTO db
    ->     (Host,Db,User,Select_priv,Insert_priv,
    ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
    ->     VALUES('localhost','bankaccount','custom',
    ->     'Y','Y','Y','Y','Y','Y');
mysql> INSERT INTO db
    ->     (Host,Db,User,Select_priv,Insert_priv,
    ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
    ->     VALUES('host47.example.com','expenses','custom',
    ->     'Y','Y','Y','Y','Y','Y');
mysql> INSERT INTO db
    ->     (Host,Db,User,Select_priv,Insert_priv,
    ->     Update_priv,Delete_priv,Create_priv,Drop_priv)
    ->     VALUES('server.domain','customer','custom',
    ->     'Y','Y','Y','Y','Y','Y');
mysql> FLUSH PRIVILEGES;

The first three INSERT statements add user table entries that allow the user custom to connect from the various hosts with the given password, but grant no global privileges (all privileges are set to the default value of 'N'). The next three INSERT statements add db table entries that grant privileges to custom for the bankaccount, expenses, and customer databases, but only when accessed from the proper hosts. As usual when you modify the grant tables directly, you must tell the server to reload them with FLUSH PRIVILEGES so that the privilege changes take effect.

To create a user who has access from all machines in a given domain (for example, mydomain.com), you can use the “%” wildcard character in the host part of the account name: 

mysql> CREATE USER 'myname'@'%.mydomain.com' IDENTIFIED BY 'mypass';

To do the same thing by modifying the grant tables directly, do this: 

mysql> INSERT INTO user (Host,User,Password,...)
    ->     VALUES('%.mydomain.com','myname',PASSWORD('mypass'),...);
mysql> FLUSH PRIVILEGES;