sql - 数据的交叉连接拆分

Question

我有一个表 Employee、另一个表 Department 和一个关系表：

Employee Table
id  Name
1   A
2   B
3   C
4   D
5   E
6   F

Department Table
id  Name
1   Accounting
2   Finance

Relation Table
id   EmployeeId   DepartmentId

我想进行一个动态查询，以便能够在我的关系表中为每个部门分配相同数量的员工，我知道我可以使用交叉连接，但会将所有员工放在每个部门中。我只想要分配，例如 3 名员工用于帐户，另外 3 名用于财务，但这个数量可能会改变。谢谢

Answer 1

这很有趣，它似乎工作得很好，员工随机分布在每个部门：

select EmployeeId, DepartmentId
from 
(  select 
    ROW_NUMBER() OVER(ORDER BY NEWID()) as RankEmployee
  , Id as EmployeeId
    from Employee
 ) e , 
(  select 
    ROW_NUMBER() OVER(ORDER BY NEWID()) as RankDepartment
  , (select count(1) from Department) as CountDepartment
  , Id as DepartmentId
    from Department
 ) d
where (RankEmployee + RankDepartment) % CountDepartment = 0

条件

(RankEmployee + RankDepartment) % CountDepartment = 0

将为每个员工只检索一行。
并且排名是随机计算的OVER(ORDER BY NEWID())。有关详细信息，请参阅此答案。

SQLFiddle 在这里。

Answer 2

declare @columns varchar(max)='',@str varchar(maX) = '',@columns1 varchar(max)=''

select   @columns = @columns+category+',' from piv group by category
set @columns= left(@columns,len(@columns)-1)

select   @columns1 = @COLUMNS1+'ISNULL(['+category+'],0) AS ['+category+'],' from piv group by category
set @columns1= left(@columns1,len(@columns1)-1)



set @str = 
'select date,'+@columns1+'  from 
(
    select date,category, amount as amounts from piv
)res
pivot
(
    max(amounts)
    for category in ('+@columns+')
)pv'
--print @str
exec(@str)