SQL查询 - 从层次结构的两个不同水平

Question

一个项目具有多个任务，其具有多个分配

获取和的

项目（1-N） - >任务（1-N） - >分配

甲任务表上的字段是计划小时数。

Assignments表上的字段是Assigned Hours。

如何在单个查询中获得所有项目的计划小时数和分配小时数？

Answer 1

select p.ProjectID, t.PlannedHoursSum, a.AssignedHoursSum 
from Projects p 
inner join (
    select ProjectID, sum(PlannedHours) as PlannedHoursSum 
    from Tasks 
    group by ProjectID 
) t on p.ProjectID = t.ProjectID 
inner join (
    select t.ProjectID, sum(AssignedHours) as AssignedHoursSum 
    from Tasks t 
    inner join Assignments a on t.TaskID = a.TaskID 
    group by t.ProjectID 
) a on p.ProjectID = a.ProjectID 

Answer 2

编辑：这个答案给出了不正确的结果，但我将它留作历史用途。

我认为这会帮助你。但我无法弄清楚如何摆脱Distinct。

Select Distinct 
     Project.ProjectId, 
     Sum(Task.PlannedHours) 
      Over (Partition By Project.ProjectId) As PlannedHours, 
     Sum(Assignment.AssignedHours) 
      Over (Partition By Project.ProjectId) As AssignedHours 
From Project 
    Inner Join Task On Project.ProjectId = Task.ProjectId 
    Inner Join Assignment On Task.TaskId= Assignment.AssignmentId 

这是我的测试脚本。

Declare @Project Table (ProjectId Int) 
Declare @Task Table (TaskId Int, ProjectId Int, PlannedHours Int) 
Declare @Assignment Table (AssignmentId Int, TaskId Int, AssignedHours Int) 

Insert Into @Project (ProjectId) values (1) 
Insert Into @Project (ProjectId) values (2) 
Insert Into @Project (ProjectId) values (3) 

Insert Into @Task (TaskId, ProjectId, PlannedHours) values (1, 1, 10) 
Insert Into @Task (TaskId, ProjectId, PlannedHours) values (2, 1, 10) 
Insert Into @Task (TaskId, ProjectId, PlannedHours) values (3, 2, 11) 
Insert Into @Task (TaskId, ProjectId, PlannedHours) values (4, 3, 12) 

Insert Into @Assignment (AssignmentId, TaskId, AssignedHours) values (1, 1, 2) 
Insert Into @Assignment (AssignmentId, TaskId, AssignedHours) values (2, 1, 2) 
Insert Into @Assignment (AssignmentId, TaskId, AssignedHours) values (3, 2, 2) 
Insert Into @Assignment (AssignmentId, TaskId, AssignedHours) values (4, 3, 3) 

Select Distinct 
     Project.ProjectId, 
     Sum(Task.PlannedHours) 
      Over (Partition By Project.ProjectId) As PlannedHours, 
     Sum(Assignment.AssignedHours) 
      Over (Partition By Project.ProjectId) As AssignedHours 
From @Project Project 
    Inner Join @Task Task On Project.ProjectId = Task.ProjectId 
    Inner Join @Assignment Assignment On Task.TaskId= Assignment.AssignmentId