How many flights depart to Hartsfield-Jackson Atlanta International from Chicago O'Hare International?
depart to refers to DEST; Hartsfield-Jackson Atlanta International refers to Description = 'Atlanta, GA: Hartsfield-Jackson Atlanta International'; depart from refers to ORIGIN; Chicago O'Hare International refes to Description = 'Chicago, IL: Chicago O'Hare International';
SELECT COUNT(FL_DATE) FROM Airlines WHERE ORIGIN = ( SELECT T2.ORIGIN FROM Airports AS T1 INNER JOIN Airlines AS T2 ON T1.Code = T2.ORIGIN WHERE T1.Description = 'Chicago, IL: Chicago O''Hare International' ) AND DEST = ( SELECT T4.DEST FROM Airports AS T3 INNER JOIN Airlines AS T4 ON T3.Code = T4.DEST WHERE T3.Description = 'Atlanta, GA: Hartsfield-Jackson Atlanta International' )