How to cancel all permissions in mysql

In mysql, you can use the REVOKE statement to delete the permissions of a specified user (specified permissions or all permissions). The syntax to cancel all permissions is "REVOKE ALL PRIVILEGES, GRANT OPTION FROM user;". For the REVOKE statement to take effect, you must have the global CREATE USER permission or UPDATE permission of the MySQL database.

The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.

In MySQL, you can use the REVOKE statement to delete some or all permissions of a user.

Delete all permissions of a specific user, the syntax format is as follows:

REVOKE ALL PRIVILEGES, GRANT OPTION FROM 用户;

You need to pay attention to the following points when deleting user permissions:

• ## The #REVOKE syntax is similar to the GRANT statement, but has the opposite effect.

• To use the REVOKE statement, you must have global CREATE USER permission or UPDATE permission on the MySQL database.

Example: Assume that the rfc user has SELECT, UPDATE, and DELETE permissions on the sample database.

To revoke all permissions from the rfc user, execute the following command:

REVOKE ALL PRIVILEGES, GRANT OPTION FROM rfc;

If rfc checks the user's permissions again, you will see that the rfc user has no permissions.

SHOW GRANTS FOR rfc; 

GRANT USAGE ON *.* TO 'rfc'@'%';

Note: USAGE permissions means there are no permissions in MySQL.

When the MySQL REVOKE command takes effect

The effect of the MySQL REVOKE statement depends on the permission level, as follows:

• Changes to global privileges only take effect when the client connects to MySQL in subsequent sessions. Changes will not be applied to all currently connected users.

• Apply changes to database permissions after the next USE statement.

• Changes to table and column permissions will apply to all queries issued after the change.

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