SQL Server - Get customers with nth order in specific date range - sql-server

Question

I'm tasked with the following:
Select a list of all customers who had their nth order during a certain date range (usually a specific month).
This list needs to contain: customer id, sum of first n orders
My tables are something like this:
[dbo.customers]: customerID
[dbo.orders]: orderID, customerID,
orderDate, orderTotal
Here is what I've tried so far:
-- Let's assume our threshold (n) is 10
-- Let's assume our date range is April 2013
-- Get customers that already had n orders before the beginning of the given date range.
DECLARE #tmpcustomers TABLE (tmpcustomerID varchar(8))
INSERT INTO
#tmpcustomers
SELECT
c.customerID
FROM
orders o
INNER JOIN customers c ON o.customerID = c.customerID
WHERE
o.orderDate < '2013-04-01'
GROUP BY c.customerID
HAVING (COUNT(o.orderID) >= 10)
-- Now get all customers that have n orders sometime within the given date range
-- but did not have n orders before the beginning of the given date range.
SELECT
a.customerID, SUM(orderTotal) AS firstTenOrderTotal
SELECT
o.customerID, o.orderID, o.orderTotal
FROM
orders o
INNER JOIN customers c ON c.customerID = o.customerID
WHERE
a.customerID NOT IN ( SELECT tmpcustomerID FROM #tmpcustomers )
AND
o.orderDate > '2013-04-01'
AND
o.orderDate < '2013-05-01'
GROUP BY c.customerID
HAVING COUNT(o.orderID) >= 10
This seems to work but it's clunky and slow. Another big problem is that the firstTenOrderTotal is actually the SUM of the total amount of orders by the end of the given date range and not necessarily the first 10.
Any suggestions for a better approach would be much appreciated.

Answer 1

In the insert to #tmpcustomers, why are you joining back to the customer table? The order table already has the customerID that you want. Also, why are you looking for orders where the order date is before your date range? Don't you just want customers with more than n orders between a date range? This will make the second query easier.
By only having the customers with n or more orders in the table variable #tmpcustomers, you should just be able to join it and the orders table in the second query to get the sum of all the orders for those customers where you would once again limit order table records to your date range (so you do not get orders outside of that range). This will remove the having statement and the join to the customers table in your final result query.

Answer 2

Give this a try. Depending on your order distribution it may perform better. In this query im assembling the list of orders in the range, and then looking back to count the number of prior orders (also grabbing the orderTotal).
note: I am assuming the orderID increments as orders are placed.
If this isnt the case just use a row_number over the date to project the sequence into the query.
declare #orders table (orderID int primary key identity(1,1), customerID int, orderDate datetime, orderTotal int)
insert into #orders (customerID, orderDate, orderTotal)
select 1, '2013-01-01', 1 union all
select 1, '2013-01-02', 2 union all
select 1, '2013-02-01', 3 union all
select 2, '2013-01-25', 5 union all
select 2, '2013-01-26', 5 union all
select 2, '2013-02-02', 10 union all
select 2, '2013-02-02', 10 union all
select 2, '2013-02-04', 20
declare #N int, #StartDate datetime, #EndDate datetime
select #N = 3,
#StartDate = '2013-02-01',
#EndDate = '2013-02-20'
select o.customerID,
[total] = o.orderTotal + p.total --the nth order + total prior
from #orders o
cross
apply ( select count(*)+1, sum(orderTotal)
from #orders
where customerId = o.customerID and
orderID < o.orderID and
orderDate <= o.orderDate
) p(n, total)
where orderDate between #StartDate and #EndDate and p.n = #N

Answer 3

Here is my suggestion:
Use Northwind
GO
select ords.OrderID , ords.OrderDate , '<-->' as Sep1 , derived1.* from
dbo.Orders ords
join
(
select CustomerID, OrderID, ROW_NUMBER() OVER(PARTITION BY CustomerID ORDER BY OrderId DESC) AS ThisCustomerCardinalOrderNumber from dbo.Orders
) as derived1
on ords.OrderID = derived1.OrderID
where
derived1.ThisCustomerCardinalOrderNumber = 3
and ords.OrderDate between '06/01/1997' and '07/01/1997'
EDIT:::::::::
I took my CTE example, and reworked it for multiple Customers (seen below).
Give it the college try.
Use Northwind
GO
declare #BeginDate datetime
declare #EndDate datetime
select #BeginDate = '01/01/1900'
select #EndDate = '12/31/2010'
;
WITH
MyCTE /* http://technet.microsoft.com/en-us/library/ms175972.aspx */
( ShipName,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry,CustomerID,CustomerName,[Address],
City,Region,PostalCode,Country,Salesperson,OrderID,OrderDate,RequiredDate,ShippedDate,ShipperName,
ProductID,ProductName,UnitPrice,Quantity,Discount,ExtendedPrice,Freight,ROWID) AS
(
SELECT
ShipName ,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry,CustomerID,CustomerName,[Address]
,City ,Region,PostalCode,Country,Salesperson,OrderID,OrderDate,RequiredDate,ShippedDate,ShipperName
,ProductID ,ProductName,UnitPrice,Quantity,Discount,ExtendedPrice,Freight
, ROW_NUMBER() OVER (PARTITION BY CustomerID ORDER BY OrderDate , ProductName ASC ) as ROWID /* Note that the ORDER BY (here) is directly related to the ORDER BY (near the very end of the query) */
FROM
dbo.Invoices inv /* “Invoices” is a VIEW, FYI */
where
(inv.OrderDate between #BeginDate and #EndDate)
)
SELECT
/*
ShipName,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry,CustomerID,CustomerName,[Address],
City,Region,PostalCode,Country,Salesperson,OrderID,OrderDate,RequiredDate,ShippedDate,ShipperName,
ProductID,ProductName,UnitPrice,Quantity,Discount,ExtendedPrice,Freight,
*/
/*trim the list down a little for the final output */
CustomerID ,OrderID , OrderDate, (ExtendedPrice + Freight) as ComputedTotal
/*The below line is the “trick”. I reference the above CTE, but only get data that is less than or equal to the row that I am on (outerAlias.ROWID)*/
, (Select SUM (ExtendedPrice + Freight) from MyCTE innerAlias where innerAlias.ROWID <= outerAlias.ROWID and innerAlias.CustomerID = outerAlias.CustomerID) as RunningTotal
, ROWID as ROWID_SHOWN_FOR_KICKS , OrderDate as OrderDate
FROM
MyCTE outerAlias
GROUP BY CustomerID ,OrderID, OrderDate, ProductName,(ExtendedPrice + Freight) ,ROWID,OrderDate
/*Two Order By Options*/
ORDER BY outerAlias.CustomerID , outerAlias.OrderDate , ProductName
/* << Whatever the ORDER BY is here, should match the “ROW_NUMBER() OVER ( ORDER BY ________ ASC )” statement inside the CTE */
/*ORDER BY outerAlias.ROWID */ /* << Or, to keep is more “trim”, ORDER BY the ROWID, which will of course be the same as the “ROW_NUMBER() OVER ( ORDER BY” inside the CTE */