Update README.md

README.md

@@ -12,6 +12,8 @@ widget:
     example_title: 'count'
   - text: 'Given the following schema:\nmountain (Mountain_ID, Name, Height, Prominence, Range, Country)\nclimber (Climber_ID, Name, Country, Time, Points, Mountain_ID)\nWrite a SQL query to list the countries that have more than one mountain.'
     example_title: 'having'
+  - text: 'Given the following schema:\nairports (apid, name, city, country, x, y, elevation, iata, icao)\nroutes (rid, dst_apid, dst_ap, src_apid, src_ap, alid, airline, codeshare)\nairlines (alid, name, iata, icao, callsign, country, active)\nWrite a SQL query to find the number of routes for each source airport and the airport name.'
+    example_title: 'join'
 ---
 
 # How to Use