TSQL - divide rows into groups based on one field - sql

Question

This is modified version of my earlier question: TSQL equally divide resultset to groups and update them
I have my database with 2 tables like so:
Orders table has data like below:
OrderID OperatorID GroupID OrderDesc Status Cash ...
--------------------------------------------------------------------------
1 1 1 small_order 1 300
2 1 1 another_order 1 0
3 1 2 xxxxxxxxxxx 2 1000
5 2 2 yyyyyyyyyyy 2 150
9 5 1 xxxxxxxxxxx 1 50
10 NULL 2 xxxxxxxxxxx 1 150
11 NULL 3 xxxxxxxxxxx 1 -50
12 4 1 xxxxxxxxxxx 1 200
Operators table:
OperatorID Name GroupID Active
---------------------------------------
1 John 1 1
2 Kate 1 1
4 Jack 2 1
5 Will 1 0
6 Sam 3 0
I'm able to equally divide my recordset into equally groups using below query:
SELECT o.*, op.operatorName AS NewOperator, op.operatorID AS NewOperatorId
FROM (SELECT o.*, (ROW_NUMBER() over (ORDER BY newid()) % numoperators) + 1 AS randseqnum
FROM Orders o CROSS JOIN
(SELECT COUNT(*) AS numoperators FROM operators WHERE operators.active=1) op
WHERE o.status in (1,3)
) o JOIN
(SELECT op.*, ROW_NUMBER() over (ORDER BY newid()) AS seqnum
FROM Operators op WHERE op.active=1
) op
ON o.randseqnum = op.seqnum ORDER BY o.orderID
Demo available at: http://sqlfiddle.com/#!3/ff47b/1
Using script from above I can divide Orders to (almost) equal groups but based on number or Orders for Operator, but I need to modify it so that it will assign Operators to Orders based on sum or Cash for orders.
For example:
If I have 6 Orders with Cash values: 300, 0, 50, 150, -50, 200 they sum gives 650.
My script should assign to 3 Operators random 2 Orders with random sum of Cash for Orders.
What I would like to get is to assign for example 300,-50 to operator1, 200, 0 to second and 150, 50 to third.
Hope this sound clear :)
Here is example output that I expect to get:
ORDERID OPERATORID GROUPID DESCRIPTION STATUS CASH NEWOPERATORID
------------------------------------------------------------------------
1 1 1 small_order 1 300 2
2 1 1 another_order 1 0 1
9 5 1 xxxxxxxxxxx 1 50 4
10 (null) 2 xxxxxxxxxxx 1 150 4
11 (null) 3 xxxxxxxxxxx 1 -50 2
12 4 1 xxxxxxxxxxx 1 200 1
How can I (if I can at all) assign Operators to my Orders so that sum or Cash will be closest to average

Answer 1

If I'm understanding this right, could you get the result you want by ordering the Cash column by the biggest, then the smallest, then the next biggest, then the next smallest, etc. Like this:
ROW_NUMBER() over (order by CASE WHEN CashOrder % 2 = 1 then Cash else -Cash END) as splitCash
where you've provided CashOrder lower in the query with
ROW_NUMBER() over (ORDER by CASH) as CashOrder
Then you specify each of your operators depending on this split value, ie (for three operators):
splitCash%3 +1