如何在树结构层次结构中对齐SQL结果集

Question

我有4个结果集需要形成树结构层次结构，如下所示：

结果集：

1. 学院
2. HeadOfDepartment
3. 教师
4. 学生

现在层次结构应该如下：

College1
   HeadOfDepartment1
       Teacher1
           Student1
           Student2
       Teacher2
           Student3
   HeadOfDepartment2
       Teacher3
           Student4
           Student5
       Teacher4
           Student6
College2
............

形成这种等级的可行解决方案是什么？  我已尝试row_number() over相应的组进行排序。
示例数据

ObjectID    Stream      Category    University  Percentage  Subject
College1    Engineering             University1     
College2    Medical                 University2  
                    ObjectID        Stream      Category    University  Percentage  Subject
Belongs to College1 HOD1        Management          
Belongs to College1 HOD2        Technical           

                ObjectID    Stream  Category    University  Percentage  Subject
Belongs to HOD1 Teacher1                                                SQL  
Belongs to HOD2 Teacher2                                                Java

                    ObjectID    Stream  Category    University  Percentage  Subject 
Belongs to Teacher1 Student1                                            90  SQL  
Belongs to Teacher2 Student2                                            80  Hibernate  

期望输出：

ObjectID    Stream      Category       University   Percentage  Subject 
College1    Engineering                University1      
HOD1        Management              
Teacher1                                                        SQL  
Student1                                            90          SQL  
HOD2        Technical       
Teacher2                                                        Java  
Student2                                            80          Hibernate 
College2    Medical                    University2      

Answer 1

使用union all的方法是：

;with combination as (
    -- Colleges
    select cast(id as char(5)) id,
        [name]
    from College
    union all 
    -- HeadOfDepartments
    select cast(CollegeId as char(5)) + cast(id as char(5))
        , '    ' + [name]
    from HeadOfDepartment
    union all
    -- Teachers
    select cast(h.CollegeId as char(5)) + cast(h.id as char(5)) + cast(t.id as char(5))
        , '        ' + t.[name]
    from Teacher t
    join HeadOfDepartment h 
      on t.HeadOfDepartmentId = h.id
    union all 
    -- Students
    select cast(h.CollegeId as char(5)) + cast(h.id as char(5)) + cast(t.id as char(5)) + cast(s.id as char(5))
        , '            ' + s.[name]
    from Student s
    join Teacher t
      on s.TeacherId = t.id
    join HeadOfDepartment h 
      on t.HeadOfDepartmentId = h.id
)
select [name]
from combination
order by id;

SQL Fiddle Demo