order by

疑问？ 怎样在order by里使用子查询时，同时查询出Income-OutCome字段的值。

SELECT Name,Sex,WorkYear,InCome-OutCome
  FROM employees,salary
    WHERE salary.EmployeeID=employees.EmployeeID
    ORDER BY 
     InCome-OutCome
    DESC
  --  等价于
  SELECT Name,Sex,WorkYear
  FROM employees
    ORDER BY 
    (SELECT InCome-OutCome
       FROM salary
         WHERE salary.EmployeeID=employees.EmployeeID)DESC