How do I join on multiple fields
The recommended approach is to have a single field in each view that is used to join multiple data sources together or to pre-join data sources that are commonly used. Sometimes, however these options are not ideal.
For situations where complex joins on multiple fields are required, use the data source tab to do the first join. Other joins can be done though the filters tab via the "Equals (Field)" operator. For instance if joining on both first name and last name on two tables. Connect the first name fields with one filter and add a second for last name.