The GRANTED BY Clause
By default, when privileges are granted in a database, the current user is recorded as the grantor.The GRANTED BY clause enables the current user to grant those privileges as another user.
When using the REVOKE statement, it will fail if the current user is not the user that was named in the GRANTED BY clause.
The GRANTED BY (and AS) clause can be used only by the database owner and other administrators.The object owner cannot use GRANTED BY unless they also have administrator privileges.