Provided herein are systems and methods for an application connector (also referred to as a reverse extract, transform, load (ETL) connector) in a database system. For example, a method includes retrieving an application connector corresponding to an application of a plurality of available applications. The application connector includes connector configuration information and connector code. A user-defined query is detected within the connector configuration information. The user-defined query is executed to obtain a query result. The query result is based on data stored in a storage device shared by the plurality of applications. The connector code of the application connector is executed to perform an update of the application, the update based on the query result.