What is a piggy-back query?
Piggy-back queries or compound queries are queries of the database that call upon yet another query within the query itself. For example, say you wanted to run a report on patients that were transferred in by either land ambulance of helicopter ambulance, but you also wanted only to look at pediatric cases. You know you want Transport Provider Mode to be either (1) land ambulance or (2) helicopter ambulance. This is an example of an either/or query: you check One or more in the query screen.
