MySQL in a Nutshell, 2nd Edition

Name

RENAME USER

Synopsis

RENAME USER 'user'[@'host'] TO 'user'[@'host'][,...]

Use this statement to change the username or the host of an existing user account. It does not change the user privileges or necessarily migrate any privileges to specific databases, events, stored routines, tables, triggers, or views. Here is an example:

RENAME USER 'michaelzabalaoui'@'localhost' TO 'zabb'@'%',
'richardstringer'@'localhost' TO 'littlerichard'@'localhost';

The first user’s name and host have been changed here, whereas the second user’s name only was changed.