MySQL Administration: Grant & Revoke privileges to a user account

Summary: in this tutorial, you will learn how to use the mysql GRANT, REVOKE statement to grant privileges to user accounts.

Introduction to the MySQL GRANT statement

The CREATE USER statement creates one or more user accounts with no privileges. It means that the user accounts can log in to the MySQL Server, but cannot do anything such as selecting a database and querying data from tables.

To allow user accounts to work with database objects, you need to grant the user accounts privileges. And the GRANT statement grants a user account one or more privileges.

The following illustrates the basic syntax of the GRANT statement:

In this syntax:

First, specify one or more privileges after the GRANT keyword. If you grant multiple privileges, you need to separate privileges by commas.

This example grants the SELECT privilege on the table employees  in the sample database to the user acount bob@localhost:

The following example grants UPDATE, DELETE, and INSERT privileges on the table employees to bob@localhost:

Second, specify the privilege_level that determines the level to which the privileges apply.

MySQL supports the following main privilege levels:

Global privileges apply to all databases in a MySQL Server. To assign global privileges, you use the *.* syntax, for example:

The account user bob@localhost can query data from all tables in all database of the current MySQL Server.

Database privileges apply to all objects in a database. To assign database-level privileges, you use the ON database_name.* syntax, for example:

In this example, bob@localhost can insert data into all tables in the classicmodels database.

Table privileges apply to all columns in a table. To assign table-level privileges, you use the ON database_name.table_name syntax, for example:

In this example, bob@localhost can delete rows from the table employees in the database classicmodels.

If you skip the database name, MySQL uses the default database or issues an error if there is no default database.

Column privileges apply to single columns in a table.  You must specify the column or columns for each privilege, for example:

In this example, bob@localhost can select data from four columns employeeNumber, lastName, firstName, and email and update only the lastName column in the employees table.

Stored routine privileges apply to stored procedures and stored functions, for example:

In this example, bob@localhost can execute the stored procedure CheckCredit in the current database.

proxy user privileges allow one user to be a proxy for another. The proxy user gets all privileges of the proxied user. For example:

In this example, alice@localhost assumes all privileges of root.

Finally, specify the account name of the user that you want to grant privileges after the TO keyword.

Notice that in order to use the GRANT statement, you must have the GRANT OPTION privilege and the privileges that you are granting. If the read_only system variable is enabled, you need to have the SUPER privilege to execute the GRANT statement.

MySQL GRANT statement examples

Typically, you use the CREATE USER statement to create a new user account first and then use the GRANT statement to grant privileges to the user.

First, create a new user called super@localhost by using the following CREATE USER statement:

Second, show the privileges assigned to super@localhost user by using the SHOW GRANTS statement.

The USAGE means that the super@localhost can log in the database but has no privilege.

Third, grant all privileges in all databases in the current database server to super@localhost:

Fourth, use the SHOW GRANTS statement again:

Permissible privileges for GRANT statement

The following table illustrates all permissible privileges that you can use for the GRANT and REVOKE statement:

Privilege	Meaning	Level
Global	Database	Table	Column	Stored Routine	Proxy
ALL [PRIVILEGES]	Grant all privileges at specified access level except GRANT OPTION
ALTER	Allow user to use of ALTER TABLEstatement	X	X	X
ALTER ROUTINE	Allow user to alter and drop stored procedures or stored functions.	X	X			X
CREATE	Allow user to create databases and tables	X	X	X
CREATE ROUTINE	Allow user to create stored procedures and stored functions	X	X
CREATE TABLESPACE	Allow user to create, alter or drop tablespaces and log file groups	X
CREATE TEMPORARY TABLES	Allow user to create a temporary table by using CREATE TEMPORARY TABLE statement	X	X
CREATE USER	Allow user to use the CREATE USER, DROP USER, RENAME USER, and REVOKE ALL PRIVILEGES statements.	X
CREATE VIEW	Allow user to create or modify the view.	X	X	X
DELETE	Allow user to use DELETE statement	X	X	X
DROP	Allow user to drop database, table and view	X	X	X
EVENT	Enable use of events for the Event Scheduler.	X	X
EXECUTE	Allow user to execute stored routines	X	X	X
FILE	Allow user to read any file in the database directory.	X
GRANT OPTION	Allow user to have privileges to grant or revoke privileges from other accounts.	X	X	X		X	X
INDEX	Allow user to create or drop indexes.	X	X	X
INSERT	Allow user to use the INSERT statement	X	X	X	X
LOCK TABLES	Allow user to use LOCK TABLES on tables for which you have the SELECT privilege	X	X
PROCESS	Allow user to see all processes with SHOW PROCESSLIST statement.	X
PROXY	Enable user proxying.
REFERENCES	Allow user to create a foreign key	X	X	X	X
RELOAD	Allow user to use FLUSH statement	X
REPLICATION CLIENT	Allow user to query to see where master or slave servers are	X
REPLICATION SLAVE	Allow the user to use replicate slaves to read binary log events from the master.	X
SELECT	Allow user to use SELECT statement	X	X	X	X
SHOW DATABASES	Allow user to show all databases	X
SHOW VIEW	Allow user to use SHOW CREATE VIEW statement	X	X	X
SHUTDOWN	Allow user to use mysqladmin shutdown command	X
SUPER	Allow user to use other administrative operations such as CHANGE MASTER TO, KILL, PURGE BINARY LOGS, SET GLOBAL, and mysqladmin command	X
TRIGGER	Allow user to use TRIGGER operations.	X	X	X
UPDATE	Allow user to use the UPDATE statement	X	X	X	X
USAGE	Equivalent to “no privileges”

Introduction to the MySQL REVOKE statement

The REVOKE statement revokes one or more privileges from a user account.

The REVOKE statement has several forms.

Revoke one or more privileges

The following illustrates the basic syntax of the REVOKE statement that revokes one or more privileges from user accounts:

In this syntax:

• First, specify a list of comma-separated privileges that you want to revoke from a user account after the REVOKE keyword.
• Second, specify the object type and privilege level of the privileges after the ON keyword; check it out the GRANT statement for more information on privilege level.
• Third, specify one or more user accounts from which you want to revoke the privileges in the FROM clause.

Note that to execute this form of REVOKE statement, you must have GRANT OPTION privilege or you must have the privileges that you are revoking.

Revoke all privileges

To revoke all privileges from a user, you use the following form of the REVOKE ALL statement:

To execute the REVOKE ALL statement, you must have the global CREATE USER privilege or the UPDATE privilege for the mysql system database.

Revoke Proxy

To revoke a proxy user, you use the REVOKE PROXY command:

A proxy user is a valid user in MySQL who can impersonate another user, therefore, the proxy user has all privileges of the user that it impersonates.

It is a good practice to show privileges of the user accounts using the SHOW GRANTS statement before you revoke the privileges from the user:

MySQL REVOKE examples

Let’s take some examples of revoking privileges.

A) Using MySQL REVOKE to revoke some privileges from a user account example

First, create a user account named rfc@localhost:

Second, grant rfc@localhost the SELECT, UPDATE, and INSERT privileges on the classicmodels database:

Third, display the granted privileges of the rfc@localhost user account:

Fourth, revoke the UPDATE and INSERT privileges from rfc@localhost:

Fifth, display the privileges of rfc@localhost:

B) Using MySQL REVOKE to revoke all privileges from a user account example

First, grant the EXECUTE privilege to the rfc@localhost:

Second, show the currently granted privileges of rfc@localhost:

Third, revoke all privileges of the rfc@localhost user account by using the REVOKE ALL statement:

Finally, show the privileges of the rfc@localhost to verify the revoke:

The rfc@localhost has no privileges. Note that USAGE privilege means no privileges in MySQL.

C) Using MySQL REVOKE to revoke PROXY privilege example

First, grant the PROXY privilege to rfc@localhost user account:

Second, show the granted privileges of rfc@localhost:

Third, revoke the PROXY privilege from the rfc@localhost:

Finally, show the granted privileges of rfc@lcoalhost to verify the revoke:

When the MySQL REVOKE command takes effect

The effect of REVOKE statement depends on the privilege level:

Global level

The changes take effect when the user account connects to the MySQL Server in the subsequent sessions. The changes are not applied to all currently connected users.

Database level

The changes take effect after the next USE statement.

Table and column levels

The changes take effect on all subsequent queries.

In this tutorial, you have learned how to use the MySQL GRANT, REVOKE statement to grant privileges to a user.