选择与相似数据集关联的对象

Question

我正在尝试从 [Company] 表中选择与至少一个其他公司共享的所有公司行，相同数量的员工（来自具有 CompanyId 列的 [Employee] 表），其中每组各个员工共享同一组 LocationId（[Employee] 表中的一列）并且比例相同。

因此，例如，该查询将选择两家公司，每家公司有 3 名员工，每个公司的 locationId 分别为 1、2 和 2。

[Employee]

 EmployeeId |  CompanyId  | LocationId | 
========================================
  1         |  1          |  1      
  2         |  1          |  2 
  3         |  1          |  2
  4         |  2          |  1 
  5         |  2          |  2 
  6         |  2          |  2 
  7         |  3          |  3



[Company]

 CompanyId | 
============
  1   |     
  2   |    
  3   |


  Returns the CompanyIds:
  ======================
  1
  2

之所以选择公司 ID 1 和 2，是因为它们与至少一家其他公司有共同之处： 1. 员工人数（3 名员工）； 2. 与这些员工关联的 LocationId 的数量/比例（1 名员工的 LocationId 为 1，2 名员工的 LocationId 为 2）。

到目前为止，我想我想使用HAVING COUNT(?) > 1 声明，但我无法弄清楚细节。有没有人有什么建议？

Answer 1

这很丑，但我能想到的唯一方法：

;with CTE as (
    select c.Id,
        (
            select e.Location, count(e.Id) [EmployeeCount]
            from Employee e
            where e.IdCompany=c.Id
            group by e.Location
            order by e.Location
            for xml auto
        ) LocationEmployeeData
    from Company c
)
select c.Id
from Company c
join (
    select x.LocationEmployeeData, count(x.Id) [CompanyCount]
    from CTE x
    group by x.LocationEmployeeData
    having count(x.Id) >= 2
) y on y.LocationEmployeeData = (select LocationEmployeeData from CTE where Id = c.Id)

见小提琴：http://www.sqlfiddle.com/#!6/6bc16/5

它通过将每个位置数据（多行）的员工人数编码为每个公司的 xml 字符串来工作。

CTE 代码本身：

select c.Id,
    (
        select e.Location, count(e.Id) [EmployeeCount]
        from Employee e
        where e.IdCompany=c.Id
        group by e.Location
        order by e.Location
        for xml auto
    ) LocationEmployeeData
from Company c

产生如下数据：

Id  LocationEmployeeData
1   <e Location="1" EmployeeCount="2"/><e Location="2" EmployeeCount="1"/>
2   <e Location="1" EmployeeCount="2"/><e Location="2" EmployeeCount="1"/>
3   <e Location="3" EmployeeCount="1"/>

然后它根据这个字符串比较公司（而不是试图确定多行是否匹配等）。

Answer 2

另一种解决方案可能如下所示。不过，它也需要提前进行性能测试（我对<> 类型的连接不太自信）。

with List as
(
  select
    IdCompany,
    Location,
    row_number() over (partition by IdCompany order by Location) as RowId,
    count(1) over (partition by IdCompany) as LocCount
  from
    Employee
) 
select
  A.IdCompany
from List as A
  inner join List as B on A.IdCompany <> B.IdCompany
  and A.RowID = B.RowID
  and A.LocCount = B.LocCount
group by
  A.IdCompany, A.LocCount
having
  sum(case when A.Location = B.Location then 1 else 0 end) = A.LocCount

相关小提琴：http://sqlfiddle.com/#!6/d9f2e/1