Cross Join Split of Data

Question

I have a table Employee, another table Department and a relational table:

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

I want to make a dynamic query to be able to distribute in my relational table same quantity of employee for each department, I know that I can use cross join but is going to put all employees in each department. I just want the distribution, for example 3 employees for Account and the other 3 for finance, but this quantity could change. Thanks

Answer 1

That was fun, it seems to work pretty well, employees are distributed randomly in each departments:

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

The condition

(RankEmployee + RankDepartment) % CountDepartment = 0

will retrieve only one row for each employee.
And ranks are computed randomly with OVER(ORDER BY NEWID()). See this answer for details.

SQLFiddle here.