查询“未定义”列时出现SQL错误（？）

Question

   SELECT Output.name, Output.avgSalary 
   FROM (SELECT Airplane.aid, Airplane.aname AS name, 
                AVG (worker.salary) AS avgSalary 
         FROM Aircraft Airplane , Certified IsCertified, Employees worker 
         WHERE Airplane.aid = IsCertified.aid AND 
               IsCertified.eid = worker.eid AND 
               Airplane.crusingrange >  1000 
          GROUP BY Airplane.aid, Airplane.aname) AS Output

Oracle SQL says error at "AS Output" near the end, yet I cannot figure out what is wrong with it. :S

ERROR at line 1:
ORA-00933: SQL command not properly ended

Answer 1

You don't need a subselect. This query is equivalent:

SELECT
    Airplane.aname AS name, 
    AVG(worker.salary) AS avgSalary 
FROM Aircraft Airplane
JOIN Certified IsCertified ON Airplane.aid = IsCertified.aid
JOIN Employees worker ON IsCertified.eid = worker.eid
WHERE Airplane.crusingrange > 1000 
GROUP BY Airplane.aid, Airplane.aname

Answer 2

try this:

         SELECT Airplane.aid, Airplane.aname AS name, 
                AVG (worker.salary) AS avgSalary 
         FROM Aircraft Airplane INNER JOIN Certified IsCertified on
                   Airplane.aid = IsCertified.aid 
              INNER JOIN Employees worker on IsCertified.eid = worker.eid
         WHERE Airplane.crusingrange >  1000 
          GROUP BY Airplane.aid, Airplane.aname