按多列

Question

我的服务有多个任务。每个任务都有一个特定向量的扣除。

我希望每个Vector_id和每个服务都查询所有Vector Deduction％。

例如我想：

Service   |   Vector   |   Deduction %
---------------------------------------
  SM      |     10     |       5
  SM      |     11     |      10
  ....
  ES      |     10     |       5    
  ....

我已经订购了我希望总结Deduction的列，但无法通过声明得到正确的分组：

Select
Service.name AS ServiceName,
Task.name AS TaskName,
Deduction.Vector_id AS DeductionVector,
Deduction.deduction AS DeductionPercentage
FROM
Task JOIN Service ON
Service.id = Task.Service_id
JOIN Deduction ON
Deduction.Task_id = Task.id    
ORDER BY ServiceName, DeductionVector;

以下是我使用的表格和一些数据：http://www.sqlfiddle.com/#!9/ea5f70

Answer 1

试试这个：

Select
    Service.name AS ServiceName,
    Task.name AS TaskName,
    Deduction.Vector_id AS DeductionVector,
    SUM(Deduction.deduction) AS DeductionPercentage
...
GROUP BY Service.name, Task.name, Deduction.Vector_id
...

请注意，您应始终Group By在Select中使用的所有列，但COUNT或SUM等汇总值除外。