Database: address_1
Question: What is the distance between the cities where Linda Smith and Tracy Kim live?
SQL:
SELECT distance FROM Direct_distance AS T1 JOIN Student AS T2 ON T1.city1_code  =  T2.city_code JOIN Student AS T3 ON T1.city2_code  =  T3.city_code WHERE T2.Fname  =  "Linda" AND T2.Lname  =  "Smith" AND T3.Fname  =  "Tracy" AND T3.Lname  =  "Kim"