GRANT ROLE <name> TO USER <user_name>

[BohuTANG]

Summary

Assigns a role to a user, granting a role to a user enables the user to perform all operations allowed by the role (through the access privileges granted to the role).

GRANT ROLE <name> TO USER <user_name>

This will discard our previous design of user with privileges grant, change to grants with role.

Notes:
A user can only have one role at a time.