TSQL Sweepstakes Script - sql

Question

I need to run a sweepstakes script to get X amount of winners from a customers table. Each customer has N participations. The table looks like this
CUSTOMER-A 5
CUSTOMER-B 8
CUSTOMER-C 1
I can always script to have CUSTOMER-A,B and C inserted 5, 8 and 1 times respectively in a temp table and then select randomly using order by newid() but would like to know if there's a more elegant way to address this.

Answer 1

(Update: Added final query.)
(Update2: Added single query to avoid temp table.)
Here's the hard part using a recursive CTE plus the final query that shows "place".
Code
DECLARE #cust TABLE (
CustomerID int IDENTITY,
ParticipationCt int
)
DECLARE #list TABLE (
CustomerID int,
RowNumber int
)
INSERT INTO #cust (ParticipationCt) VALUES (5)
INSERT INTO #cust (ParticipationCt) VALUES (8)
INSERT INTO #cust (ParticipationCt) VALUES (1)
INSERT INTO #cust (ParticipationCt) VALUES (3)
INSERT INTO #cust (ParticipationCt) VALUES (4)
SELECT * FROM #cust
;WITH t AS (
SELECT
lvl = 1,
CustomerID,
ParticipationCt
FROM #Cust
UNION ALL
SELECT
lvl = lvl + 1,
CustomerID,
ParticipationCt
FROM t
WHERE lvl < ParticipationCt
)
INSERT INTO #list (CustomerID, RowNumber)
SELECT
CustomerID,
ROW_NUMBER() OVER (ORDER BY NEWID())
FROM t
--<< All rows
SELECT * FROM #list ORDER BY RowNumber
--<< All customers by "place"
SELECT
CustomerID,
ROW_NUMBER() OVER (ORDER BY MIN(RowNumber)) AS Place
FROM #list
GROUP BY CustomerID
Results
CustomerID ParticipationCt
----------- ---------------
1 5
2 8
3 1
4 3
5 4
CustomerID RowNumber
----------- -----------
4 1
1 2
1 3
2 4
1 5
5 6
2 7
2 8
4 9
2 10
2 11
2 12
1 13
5 14
5 15
3 16
5 17
1 18
2 19
2 20
4 21
CustomerID Place
----------- -----
4 1
1 2
2 3
5 4
3 5
Single Query with No Temp Table
It is possible to get the answer with a single query that does not use a temp table. This works fine, but I personally like the temp table version better so you can validate the interim results.
Code (Single Query)
;WITH List AS (
SELECT
lvl = 1,
CustomerID,
ParticipationCt
FROM #Cust
UNION ALL
SELECT
lvl = lvl + 1,
CustomerID,
ParticipationCt
FROM List
WHERE lvl < ParticipationCt
),
RandomOrder AS (
SELECT
CustomerID,
ROW_NUMBER() OVER (ORDER BY NEWID()) AS RowNumber
FROM List
)
SELECT
CustomerID,
ROW_NUMBER() OVER (ORDER BY MIN(RowNumber)) AS Place
FROM RandomOrder
GROUP BY CustomerID

Answer 2

try this:
Select Top X CustomerId
From (Select CustomerId,
Rand(CustomerId) *
Count(*) /
(Select Count(*)
From Table) Sort
From Table
Group By CustomerId) Z
Order By Sort Desc
EDIT: abovbe assumed multiple rows per customer, one row per participation... Sorry, following assumes one row per customer, with column Participations holding number of participations for that customer.
Select Top 23 CustomerId
From ( Select CustomerId,
Participations - RAND(CustomerId) *
(Select SUM(Participations ) From customers) sort
from customers) Z
Order By sort desc