JOIN, GROUP BY AND SUM in single Query - sql

Question

Invoices Table
invoice_id invoice_date
------------ --------------
1 2013-11-27
2 2013-10-09
3 2013-09-12
Orders Table
order_id invoice_id product quantity total
--------- ---------- --------- --------- -------
1 1 Product 1 100 1000
2 1 Product 2 50 200
3 2 Product 1 40 400
4 3 Product 2 50 200
And i want a single sql query that produces following result
products Month 9 Total Month 10 Total Mont 11 Total
-------- ------------- -------------- -------------
Product 1 0 400 100
Product 2 200 0 200
I have tried the following sql query
SELECT orders.products, DATEPART(Year, invoices.invoice_date) Year, DATEPART(Month, invoices.invoice_date) Month, SUM(orders.total) [Total],
FROM invoices INNER JOIN orders ON invoices.invoice_id=orders.invoice_id
GROUP BY orders.products, DATEPART(Year, invoices.invoice_date), DATEPART(Month, invoices.invoice_date)
But it returns nothing. Is it possible to get this result with single query and what should i do for that ? Thanks

Answer 1

I think you want to use PIVOT here ...
Try this:
WITH tmp
AS
(
SELECT orders.products,
DATEPART(Year, invoices.invoice_date) Year,
DATEPART(Month, invoices.invoice_date) Month,
SUM(orders.total) [Total]
FROM invoices INNER JOIN orders ON invoices.invoice_id = orders.invoice_id
GROUP BY
orders.products,
DATEPART(Year, invoices.invoice_date),
DATEPART(Month, invoices.invoice_date)
)
SELECT products,
ISNULL([9],0) AS Nine, ISNULL([10],0) AS Ten, ISNULL([11],0) as Eleven
FROM tmp
PIVOT
(
SUM([Total])
FOR Month IN
( [9], [10], [11])
) as PVT;
You can edit it here: http://sqlfiddle.com/#!6/6f80f/6

Answer 2

You better use pivot for this. Just remember that you have to list every month explicitly in pivot..for..in clause.
select
*
into #invoices
from (
select 1 as invoice_id, '2013-11-27' as invoice_date union all
select 2,'2013-10-09' union all
select 3,'2013-09-12'
) x
select
*
into #orders
from (
select 1 as order_id,1 as invoice_id,'Product 1' as product,100 as quantity,1000 as total union all
select 2,1,'Product 2',50,200 union all
select 3,2,'Product 1',40,400 union all
select 4,3,'Product 2',50,200
) x
GO
select
Product,
[9], [10], [11]
from (
select
o.product, datepart([month],i.invoice_date) as mon,
o.total
from #invoices i
join #orders o
on i.invoice_id=o.invoice_id
) x
pivot (
sum(total) for mon in ([9],[10],[11])
) p

Answer 3

One way to do it is with Cases:
Select
O.product,
Sum(Case
When DATEPART(M, I.invoice_Date) = 9 Then O.total
Else 0
End) as Month9,
Sum(Case
When DATEPART(M, I.invoice_Date) = 10 Then O.total
Else 0
End) as Month10,
Sum(Case
When DATEPART(M, I.invoice_Date) = 11 Then O.total
Else 0
End) as Month11
From Invoice I
Left join Orders O on I.invoice_id = O.invoice_id
Group by O.product
There is another way using Pivots (depending on your version of SQL).
Select product, [9], [10], [11]
From
(
Select O.Product, O.total, DatePart(M, I.Invoice_Date) as [MonthNum]
From Invoice I
Left join Orders O on I.invoice_id = O.invoice_id
) P
PIVOT
(
Sum(P.total)
For [MonthNum] in ([9], [10], [11])
) as O