If you often need to use a database table from MapR-DB, then you may want to centralize the connection information to MapR-DB and the table schema details in the Metadata folder in the Repository tree view.
Even though you can do this from the DB connection node, using the Hadoop cluster node is recommended in order to make better use of the centralized connection properties for a given MapR distribution.
Launch the MapR distribution you need to use and ensure that you have the proper access permission to that distribution and its MapR-DB database.
Create the connection to that MapR distribution from the Hadoop cluster node. For further information, see Centralizing a Hadoop connection.