SQL query of sales by customer over multiple years for top 50 customers in one year - sql

Question

I have a query in SQL server that successfully returns the top 50 customers for a given year by sales. I want to expand it to return their sales for the additional years when they may or may not be in the top 50.
SELECT TOP 50 CU.CustomerName, SUM(ART.SalesAnalysis) AS '2011'
FROM ARTransaction AS ART, Customer AS CU
WHERE ART.CustomerN = CU.CustomerN AND ART.PostingDate BETWEEN '2010-12-31' AND '2012-01-01'
GROUP By CU.CustomerName
ORDER BY SUM(ART.SalesAnalysis) DESC
I tried adding nested SELECT statements but they return strange results and I'm not sure why (might not ever work, but the results have me flabbergasted anyway). When included the values of every row is changed and customers are duplicated.
(SELECT SUM(ART.SalesAnalysis)
WHERE ART.PostingDate BETWEEN '2011-12-31' AND '2013-01-01') AS '2012'
I tried to put a TOP statement in a nested SELECT in HAVING but that tells me
"Msg 8114, Level 16, State 5, Line 1
Error converting data type varchar to numeric."
SELECT CU.CustomerName, SUM(ART.SalesAnalysis) AS '2011'
FROM ARTransaction AS ART
JOIN Customer AS CU ON ART.CustomerN = CU.CustomerN
GROUP BY CU.CustomerNAme
HAVING CU.CustomerNAme IN
(SELECT TOP 50 CU.CustomerName
FROM ARTransaction
JOIN Customer ON ARTransaction.CustomerN = Customer.CustomerN
WHERE ARTransaction.SalesAnalysis BETWEEN '2010-12-31' AND '2012-01-01'
GROUP BY Customer.CustomerN
ORDER BY SUM(ART.SalesAnalysis) DESC)

Answer 1

If I understand correctly, you are looking for the top 50 sales for customers based on 2011 data - and want to see all years data for those top 50 from 2011, regardless of those customers being in the top 50 for other years.
Try this, it might need to be tweaked a bit as I don't know the schema, but if I understand the question correctly, this should do the trick.
WITH Top50 AS (
SELECT TOP 50
CU.CustomerN
,SUM(ART.SalesAnalysis) AS SalesTotal
FROM
ARTransaction art
INNER JOIN
Customer cu
ON cu.CustomerN = art.CustomerN
WHERE
ART.PostingDate BETWEEN CAST('2011-01-01' AS DATETIME)
AND CAST('2011-12-31' AS DATETIME)
GROUP BY
CU.CustomerN
ORDER BY
SUM(ART.SalesAnalysis) DESC)
SELECT
c.CustomerName
,SUM(a.SalesAnalysis) AS TotalSales
,YEAR(a.PostingDate) AS PostingDateYear
FROM
ARTransaction a
INNER JOIN
Customer c
ON c.CustomerN = a.CustomerN
INNER JOIN
Top50 t
ON t.CustomerN = a.CustomerN
GROUP BY
c.CustomerName
,YEAR(a.PostingDate)
ORDER BY
PostingDateYear

Answer 2

you could use something like below... you will be looking at the all the data for all the years you want to look at and then just getting the top 50 for the 2011 year
SELECT TOP 50
CU.CustomerName,
SUM(case when year(ART.PostingDate) = 2011 -- or you could use case when ART.PostingDate BETWEEN '2011-01-01' AND '2011-12-31'
then ART.SalesAnalysis
else 0 end) AS 2011,
SUM(case when year(ART.PostingDate) = 2012
then ART.SalesAnalysis
else 0 end) AS 2012
FROM
ARTransaction ART,
inner join Customer CU
on ART.CustomerN = CU.CustomerN
WHERE ART.PostingDate BETWEEN '2011-01-01 AND '2012-12-31'
GROUP By CU.CustomerName
ORDER BY
SUM(case when year(ART.PostingDate) = 2011
then ART.SalesAnalysis
else 0 end) DESC