• MySQL 5.1 Reference Manual :: 5 MySQL Server Administration :: 5.4 The MySQL Access Privilege System :: 5.4.1 Privileges Provided by MySQL
  • 5.4.1. Privileges Provided by MySQL

    MySQL provides privileges that apply in different contexts and at different levels of operation:

    • Administrative privileges enable users to manage operation of the MySQL server. These privileges are global because they are not specific to a particular database.

    • Database privileges apply to a database and to all objects within it. These privileges can be granted for specific databases, or globally so that they apply to all databases.

    • Privileges for database objects such as tables, indexes, views, and stored routines can be granted for specific objects within a database, for all objects of a given type within a database (for example, all tables in a database), or globally for all objects of a given type in all databases).

    Information about account privileges is stored in the user, db, host, tables_priv, columns_priv, and procs_priv tables in the mysql database (see Section 5.4.2, “Privilege System Grant Tables”). The MySQL server reads the contents of these tables into memory when it starts and reloads them under the circumstances indicated in Section 5.4.6, “When Privilege Changes Take Effect”. Access-control decisions are based on the in-memory copies of the grant tables.

    Some releases of MySQL introduce changes to the structure of the grant tables to add new access privileges or features. Whenever you update to a new version of MySQL, you should update your grant tables to make sure that they have the current structure so that you can take advantage of any new capabilities. See Section 4.4.8, “mysql_upgrade — Check Tables for MySQL Upgrade”.

    The following table shows the privilege names used at the SQL level in the GRANT and REVOKE statements, along with the column name associated with each privilege in the grant tables and the context in which the privilege applies.

    Privilege Column Context
    CREATE Create_priv databases, tables, or indexes
    DROP Drop_priv databases or tables
    GRANT OPTION Grant_priv databases, tables, or stored routines
    REFERENCES References_priv databases or tables
    EVENT Event_priv databases
    ALTER Alter_priv tables
    DELETE Delete_priv tables
    INDEX Index_priv tables
    INSERT Insert_priv tables
    SELECT Select_priv tables
    UPDATE Update_priv tables
    CREATE TEMPORARY TABLES Create_tmp_table_priv tables
    LOCK TABLES Lock_tables_priv tables
    TRIGGER Trigger_priv tables
    CREATE VIEW Create_view_priv views
    SHOW VIEW Show_view_priv views
    ALTER ROUTINE Alter_routine_priv stored routines
    CREATE ROUTINE Create_routine_priv stored routines
    EXECUTE Execute_priv stored routines
    FILE File_priv file access on server host
    CREATE USER Create_user_priv server administration
    PROCESS Process_priv server administration
    RELOAD Reload_priv server administration
    REPLICATION CLIENT Repl_client_priv server administration
    REPLICATION SLAVE Repl_slave_priv server administration
    SHOW DATABASES Show_db_priv server administration
    SHUTDOWN Shutdown_priv server administration
    SUPER Super_priv server administration
    ALL [PRIVILEGES]   server administration
    USAGE   server administration

    The following list provides a general description of each privilege available in MySQL. Particular SQL statements might have more specific privilege requirements than indicated here. If so, the description for the statement in question provides the details.

    • The ALL or ALL PRIVILEGES privilege specifier is shorthand. It stands for “all privileges available at a given privilege level” (except GRANT OPTION). For example, granting ALL at the global or table level grants all global privileges or all table-level privileges.

    • The ALTER privilege enables use of ALTER TABLE to change the structure of or rename tables. (ALTER TABLE also requires the INSERT and CREATE privileges.)

      MySQL Enterprise.  In some circumstances, the ALTER privilege is entirely unnecessary—on slaves where there are no nonreplicated tables, for instance. The MySQL Enterprise Monitor notifies subscribers when accounts have inappropriate privileges. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

    • The ALTER ROUTINE privilege is needed to alter or drop stored routines (procedures and functions).

    • The CREATE privilege enables creation of new databases and tables.

    • The CREATE ROUTINE privilege is needed to create stored routines (procedures and functions).

    • The CREATE TEMPORARY TABLES privilege enables the use of the keyword TEMPORARY in CREATE TABLE statements.


    • The CREATE VIEW privilege enables use of CREATE VIEW.

    • The DELETE privilege enables rows to be deleted from tables in a database.

    • The DROP privilege enables you to drop (remove) existing databases, tables, and views. Beginning with MySQL 5.1.10, the DROP privilege is also required in order to use the statement ALTER TABLE ... DROP PARTITION on a partitioned table. Beginning with MySQL 5.1.16, the DROP privilege is required for TRUNCATE TABLE (before that, TRUNCATE TABLE requires the DELETE privilege). If you grant the DROP privilege for the mysql database to a user, that user can drop the database in which the MySQL access privileges are stored.

    • The EVENT privilege is required to create, alter, or drop events for the Event Scheduler. This privilege was added in MySQL 5.1.6.

    • The EXECUTE privilege is required to execute stored routines (procedures and functions).

    • The FILE privilege gives you permission to read and write files on the server host using the LOAD DATA INFILE and SELECT ... INTO OUTFILE statements and the LOAD_FILE() function. A user who has the FILE privilege can read any file on the server host that is either world-readable or readable by the MySQL server. (This implies the user can read any file in any database directory, because the server can access any of those files.) The FILE privilege also enables the user to create new files in any directory where the MySQL server has write access. As a security measure, the server will not overwrite existing files.

    • The GRANT OPTION privilege enables you to give to other users or remove from other users those privileges that you yourself possess.

    • The INDEX privilege enables you to create or drop (remove) indexes. INDEX applies to existing tables. If you have the CREATE privilege for a table, you can include index definitions in the CREATE TABLE statement.

    • The INSERT privilege enables rows to be inserted into tables in a database. INSERT is also required for the ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR TABLE table-maintenance statements.

    • The LOCK TABLES privilege enables the use of explicit LOCK TABLES statements to lock tables for which you have the SELECT privilege. This includes the use of write locks, which prevents other sessions from reading the locked table.

    • The PROCESS privilege pertains to display of information about the threads executing within the server (that is, information about the statements being executed by sessions). The privilege enables use of SHOW PROCESSLIST or mysqladmin processlist to see threads belonging to other accounts; you can always see your own threads.

    • The REFERENCES privilege currently is unused.

    • The RELOAD privilege enables use of the FLUSH statement. It also enables mysqladmin commands that are equivalent to FLUSH operations: flush-hosts, flush-logs, flush-privileges, flush-status, flush-tables, flush-threads, refresh, and reload.

      The reload command tells the server to reload the grant tables into memory. flush-privileges is a synonym for reload. The refresh command closes and reopens the log files and flushes all tables. The other flush-xxx commands perform functions similar to refresh, but are more specific and may be preferable in some instances. For example, if you want to flush just the log files, flush-logs is a better choice than refresh.

    • The REPLICATION CLIENT privilege enables the use of SHOW MASTER STATUS and SHOW SLAVE STATUS.

    • The REPLICATION SLAVE privilege should be granted to accounts that are used by slave servers to connect to the current server as their master. Without this privilege, the slave cannot request updates that have been made to databases on the master server.

    • The SELECT privilege enables you to select rows from tables in a database. SELECT statements require the SELECT privilege only if they actually retrieve rows from a table. Some SELECT statements do not access tables and can be executed without permission for any database. For example, you can use SELECT as a simple calculator to evaluate expressions that make no reference to tables:

      SELECT 1+1;
      SELECT PI()*2;

      The SELECT privilege is also needed for other statements that read column values. For example, SELECT is needed for columns referenced on the right hand side of col_name=expr assignment in UPDATE statements or for columns named in the WHERE clause of DELETE or UPDATE statements.

    • The SHOW DATABASES privilege enables the account to see database names by issuing the SHOW DATABASE statement. Accounts that do not have this privilege see only databases for which they have some privileges, and cannot use the statement at all if the server was started with the --skip-show-database option. Note that any global privilege is a privilege for the database.

      MySQL Enterprise.  The SHOW DATABASES privilege should be granted only to users who need to see all the databases on a MySQL server. Subscribers to the MySQL Enterprise Monitor are alerted when servers are started without the --skip-show-database option. For more information, see http://www.mysql.com/products/enterprise/advisors.html.

    • The SHOW VIEW privilege enables use of SHOW CREATE VIEW.

    • The SHUTDOWN privilege enables use of the mysqladmin shutdown command. There is no corresponding SQL statement.

    • The SUPER privilege enables an account to use CHANGE MASTER TO, KILL or mysqladmin kill to kill threads belonging to other accounts (you can always kill your own threads), PURGE BINARY LOGS, configuration changes via SET GLOBAL to modify global system variables, the mysqladmin debug command, enabling or disabling logging, performing updates even if the read_only system variable is enabled, starting and stopping replication on slave servers, specification of any account in the DEFINER attribute of stored programs and views, and allows you to connect (once) even if the connection limit controlled by the max_connections system variable is reached.

      To create or alter stored functions if binary logging is enabled, you may also need the SUPER privilege, as described in Section 19.7, “Binary Logging of Stored Programs”.

    • The TRIGGER privilege enables you to create and drop triggers. You must have this privilege for a table to create or drop triggers for that table. This privilege was added in MySQL 5.1.6. (Prior to MySQL 5.1.6, trigger operations required the SUPER privilege.)

    • The UPDATE privilege enables rows to be updated in tables in a database.

    • The USAGE privilege specifier stands for “no privileges.” It is used at the global level with GRANT to modify account attributes such as resource limits or SSL characteristics without affecting existing account privileges.

    It is a good idea to grant to an account only those privileges that it needs. You should exercise particular caution in granting the FILE and administrative privileges:

    • The FILE privilege can be abused to read into a database table any files that the MySQL server can read on the server host. This includes all world-readable files and files in the server's data directory. The table can then be accessed using SELECT to transfer its contents to the client host.

    • The GRANT OPTION privilege enables users to give their privileges to other users. Two users that have different privileges and with the GRANT OPTION privilege are able to combine privileges.

    • The ALTER privilege may be used to subvert the privilege system by renaming tables.

    • The SHUTDOWN privilege can be abused to deny service to other users entirely by terminating the server.

    • The PROCESS privilege can be used to view the plain text of currently executing statements, including statements that set or change passwords.

    • The SUPER privilege can be used to terminate other sessions or change how the server operates.

    • Privileges granted for the mysql database itself can be used to change passwords and other access privilege information. Passwords are stored encrypted, so a malicious user cannot simply read them to know the plain text password. However, a user with write access to the user table Password column can change an account's password, and then connect to the MySQL server using that account.

      MySQL Enterprise.  Accounts with unnecessary global privileges constitute a security risk. Subscribers to the MySQL Enterprise Monitor are automatically alerted to the existence of such accounts. For detailed information, see http://www.mysql.com/products/enterprise/advisors.html.