查询 "undefined"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 在接近尾声的“AS 输出”处说错误，但我无法弄清楚它有什么问题。 :S

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

Answer 1

您不需要子选择。这个查询是等价的:

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