CREATE TABLE on_call (nurse VARCHAR2)
CREATE TABLE nurse (name VARCHAR2, EmployeeID VARCHAR2)

Find the names of nurses who are on call.
SELECT DISTINCT T1.name FROM nurse AS T1 JOIN on_call AS T2 ON T1.EmployeeID = T2.nurse
SELECT DISTINCT "T1"."name" FROM "nurse" "T1" JOIN "on_call" "T2" ON "T1"."EmployeeID" = "T2"."nurse"