text: CREATE TABLE Flight (origin VARCHAR) -- Which origin has most number of flights? SELECT origin FROM Flight GROUP BY origin ORDER BY COUNT(*) DESC LIMIT 1 CREATE TABLE Flight (destination VARCHAR) -- Which destination has least number of flights? SELECT destination FROM Flight GROUP BY destination ORDER BY COUNT(*) LIMIT 1 CREATE TABLE Flight (aid VARCHAR, flno VARCHAR); CREATE TABLE Aircraft (name VARCHAR, aid VARCHAR) -- What is the aircraft name for the flight with number 99 SELECT T2.name FROM Flight AS T1 JOIN Aircraft AS T2 ON T1.aid = T2.aid WHERE T1.flno = 99 CREATE TABLE Flight (flno VARCHAR, aid VARCHAR); CREATE TABLE Aircraft (aid VARCHAR, name VARCHAR) -- Show all flight numbers with aircraft Airbus A340-300. SELECT T1.flno FROM Flight AS T1 JOIN Aircraft AS T2 ON T1.aid = T2.aid WHERE T2.name = "Airbus A340-300" CREATE TABLE Aircraft (name VARCHAR, aid VARCHAR); CREATE TABLE Flight (aid VARCHAR) -- Show aircraft names and number of flights for each aircraft. SELECT T2.name, COUNT(*) FROM Flight AS T1 JOIN Aircraft AS T2 ON T1.aid = T2.aid GROUP BY T1.aid CREATE TABLE Aircraft (name VARCHAR, aid VARCHAR); CREATE TABLE Flight (aid VARCHAR) -- Show names for all aircraft with at least two flights. SELECT T2.name FROM Flight AS T1 JOIN Aircraft AS T2 ON T1.aid = T2.aid GROUP BY T1.aid HAVING COUNT(*) >= 2 CREATE TABLE Certificate (eid VARCHAR) -- How many employees have certificate. SELECT COUNT(DISTINCT eid) FROM Certificate