查詢「未定義」列（？）時出現SQL錯誤

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在最後的「AS輸出」中表示錯誤，但我無法弄清楚它出了什麼問題。 ：S

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

Answer 1

試試這個：

  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 

Answer 2

你不需要子選擇。這種查詢是等效的：

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