You can edit a BigQuery connection to add tables and columns.
To edit a connection:
Click Data in the top navigation bar.
Click the Connections tab.
Click the name of the connection you want to edit.
Click Edit connection at the upper-right-hand side of the page.
By default, the Select tables page appears. You have the option, though, to change the connection name and update the connection details, by clicking the appropriate option at the top of the screen, making any changes needed and clicking Continue to go to the next page.
Expand the database table drop-down menu, and select the tables and columns you want to add.
Click Update, and then click Confirm to save the updated connection detail.
To remove a table from a connection, delete it from the connection details page. For more information, see: Delete a table.
See the Connection reference for details of connection parameters.