我可以在SQL中选择一组平均值

Question

我可以根据SQL中的字段选择一组平均值吗？类似：

SELECT 
    AVG(Salary WHERE department = 1) as AvgDept1,
    AVG(Salary WHERE title = 1) as AvgTitle1,
    AVG(TimeOnJob WHERE title = 1 and department = 1) as AvgTime1
FROM
    Employees

我知道这与一个小组的AVG相似，但我无法围绕如何从中获取三个值的头。

Answer 1

看起来像三个单独的查询，如果您希望它们捆绑成一个选择，则可以做以下操作：

SELECT 
   (SELECT AVG(Salary) WHERE department = 1 FROM Employees) AS AvgDept1,
   (SELECT AVG(Salary)  WHERE title = 1 FROM Employees) AS AvgTitle1
   (select AVG(TimeOnJob) WHERE title = 1 and department = 1 FROM Employees) AS AvgTime1