Build customers report of last years with T-SQL - sql

Question

I've 3 tables (simplified):
-----------Orders--------------------
Id | Total_Price | Customer_Id | Date
--------Order Details---------------------
Id | Order_Id | Product Name | Qty | Value
----Customers------
Id | Name | Address
I take a total order value of single customer with this query:
SELECT C.ID, C.NAME , SUM(O.TOTAL_PRICE)
FROM CUSTOMERS C
JOIN ORDERS O ON O.CUSTOMER_ID = C.ID
GROUP BY C.ID, C.NAME
Now, I want to build a report with total order value filtered by a range of dates:
SELECT C.ID, C.NAME , SUM(O.TOTAL_PRICE)
FROM CUSTOMERS C
JOIN ORDERS O ON O.CUSTOMER_ID = C.ID
WHERE O.DATE BETWEEN #value1 AND #value2
GROUP BY C.ID, C.NAME
this works OK, but I want to select last 3 year sums of total orders value grouped by customer, this is the results that I want:
1Year | 2Year | 3Year | Customer_Name
-------------------------------------------------
XXX | YYY | ZZZZ | Customer1
XYX | YYZ | ZZTZ | Customer2
....
I've this cardinality:
Customer table with 22.000 rows
Orders table with 87.000 rows
Orders details with 600.000
It is possible without temptable,vartable or stored procedure with long execution time?
In my report I want also to calculate total Qty of last 3 years grouped by customer of a product, but this is the next step.
Any ideas?
Thanks

Answer 1

You can use a case statement to get the result you want. Since there is some ambiguity in your post about how the year ranges are defined, I've left out any calculations to get those year end/starts and just put variables in. You can revise to suit your need.
SELECT C.ID
,C.NAME
,SUM(CASE
WHEN o.DATE BETWEEN #year1start
AND #year1end
THEN O.TOTAL_PRICE
ELSE 0
END) Year1
,SUM(CASE
WHEN o.DATE BETWEEN #year2start
AND #year2end
THEN O.TOTAL_PRICE
ELSE 0
END) Year2
,SUM(CASE
WHEN o.DATE BETWEEN #year3start
AND #year3end
THEN O.TOTAL_PRICE
ELSE 0
END) Year3
FROM CUSTOMERS C
INNER JOIN ORDERS O ON O.CUSTOMER_ID = C.ID
GROUP BY C.ID
,C.NAME

Answer 2

Another option is to use pivot statement. I assume every your date range equals to one year (e.g. 2013, 2014 and so on).
If these years are strongly determined pivot isn't very beautiful option (look at full sqlfiddle example, it has possible solution for your additional question):
select
c.Id, c.Name, c.Address, CostByYear.[2013], CostByYear.[2014], CostByYear.[2015]
from Customers c
left join (
select
pt.Customer_Id, isnull(pt.[2013], 0) as [2013],
isnull(pt.[2014], 0) as [2014], isnull(pt.[2015], 0) as [2015]
from (
select
o.Customer_Id, year(o.Date) [Year], sum(o.Total_Price) [TotalCost]
from Orders o
group by
o.Customer_Id, year(o.Date)
) src
pivot (
sum(TotalCost) for [Year] in ([2013], [2014], [2015])
) pt
) CostByYear on
c.Id = CostByYear.Customer_Id
order by
c.Name
Also you can do both approaches (mine and prev answer) with dynamically created queries if year ranges aren't known and strongly defined.