MySQL 8 Cookbook

Modifying the mysql.user table

All the user information, along with privileges, is stored in the mysql.user table. If you have the privilege to access the mysql.user table, you can directly modify the mysql.user table to create users and grant privileges.

If you modify the grant tables indirectly, using account-management statements such as GRANT, REVOKE, SET PASSWORD, or RENAME USER, the server notices these changes and loads the grant tables into memory again immediately.

If you modify the grant tables directly, using statements such as INSERT, UPDATE, or DELETE, your changes have no effect on privilege checking until you either restart the server or tell it to reload the tables. If you change the grant tables directly but forget to reload ...