Disclosed is a method for managing database permissions, the method including: obtaining a login account that successfully logs in to a first database, where the first database is a relational database built in with permission management and is pre-configured with an external table that has a mapping relationship with a second database; ascertaining management permissions of the login account based on pre-configured management permission information; determining whether a management operation on the external table by the login account exceeds the management permissions of the login account; and if the management operation by the login account does not exceed its management permissions, permitting the management operation, and synchronizing the management operation to the second database based on the mapping relationship between the external table and the second database. Further disclosed are a system and a device for managing database permissions, as well as a computer-readable storage medium.