I work for a trucking company, and we're interested in getting a count of the number of times one of our trucks travels between two cities, in either direction.
I have a table that lists an origin and destination for each trip segment, such as:
Origin Destination
City 1 City 2 City 2 City 1 City 3 City 4 City 2 City 1
I need a query that tells me that there were three trips between City 1 and City 2 and one trip between City 3 and City 4. Thanks very much!