How to get a difference between two query result sets - sql

Question

I have two queries. The output for the first query is the total sales quantity for all Brands and the output for the second query is the total sales quantity only for 'New' Brands.
I need to create only one query (By merging below two queries: Query1 & Query2) where we can see the total sales of 'New' brands per Region, total sales of All brands per region and a new column named difference (Total sales quantity of All brands- Total sales quantity of New brands) side by side.
Expected Output :
InvoiceDate
Brand
Region
Quantity for 'New' Brand
Quantity for All Brand
Difference
2021/10/01
New
A
40
100
60
2021/10/01
New
B
10
90
80
2021/10/01
New
C
50
150
100
2021/10/01
New
D
30
200
170
These are my queries:
Query1:
SELECT InvoiceDate, Brand, Region, Quantity From TotalSales // For All Brands
Query2:
SELECT InvoiceDate, Brand, Region, Quantity From TotalSales where Brand='New' // For New Brands

Answer 1

There are a couple of ways of doing this...
First - I don't think you want the "Brand" column in your result. That doesn't make must sense. Also, I think you are going to want a summation for the AllBrands total...
Use subqueries
select allBrands.InvoiceDate, allBrands.Region, newBrands.Quantity as NewQuantity, allBrands.Quantity as allQuantity, allBrands.Quantity-newBrands.Quantity as Difference
FROM
(SELECT InvoiceDate, Region, SUM(Quantity) as Quantity From TotalSales GROUP BY InvoiceDate, Region) as allBrands
LEFT OUTER JOIN (SELECT InvoiceDate, Region, Quantity From TotalSales where Brand='New') as NewBrands ON NewBrands.InvoiceDate = allBrands.InvoiceDate AND NewBrands.Region = AllBrands.Region
or 2. use temp tables
SELECT InvoiceDate, Region, SUM(Quantity) as Quantity INTO #allSales From TotalSales GROUP BY InvoiceDate, Region;
SELECT InvoiceDate, Region, Quantity INTO #newSales From TotalSales where Brand='New';
select allBrands.InvoiceDate, allBrands.Region, newBrands.Quantity as NewQuantity, allBrands.Quantity as allQuantity, allBrands.Quantity-newBrands.Quantity as Difference
FROM #allBrands allBrands
LEFT OUTER JOIN #newBrands newBrands ON NewBrands.InvoiceDate = allBrands.InvoiceDate AND NewBrands.Region = AllBrands.Region;

Answer 2

You want to get the quantity for brand = 'new' and the total quantity for all brands and compare the two.
One way to achieve this is conditional aggregation:
select
invoicedate,
'New' as brand,
region,
sum(case when brand = 'New' then quantity else 0 end) as qty_new,
sum(quantity) as qty_all,
sum(quantity) - sum(case when brand = 'New' then quantity else 0 end) as diff
from totalsales
group by invoicedate, region
having sum(case when brand = 'New' then quantity else 0 end) > 0
order by invoicedate, region;
Another is a join
with qnew as
(
select invoicedate, brand, region, quantity
from totalsales
where brand = 'New'
)
, qall as
(
select invoicedate, region, sum(quantity) as total
from totalsales
group by invoicedate, region
)
select
qnew.*, qall.total, qall.total- qnew.quantity as diff
from qnew
join qall on qall.invoicedate = qnew.invoicedate
and qall.brand = qnew.brand
and qall.region = qnew.region
order by qnew.invoicedate, qnew.brand, qnew.region;

Answer 3

You can use simple conditional aggregation (SUM) on the data such as this:
DECLARE #TotalSales TABLE (InvoiceDate DATE, Brand NVARCHAR(16), Region NCHAR(1), Quantity INT)
INSERT INTO
#TotalSales(
InvoiceDate,
Brand,
Region,
Quantity
)
VALUES ('10/1/2021', 'New', 'A', 20),
('10/1/2021', 'New', 'A', 20),
('10/1/2021', 'Old', 'A', 30),
('10/1/2021', 'Old', 'A', 30),
('10/1/2021', 'New', 'B', 10),
('10/1/2021', 'Old', 'B', 30),
('10/1/2021', 'Old', 'B', 50),
('10/1/2021', 'New', 'C', 50),
('10/1/2021', 'Old', 'C', 100),
('10/1/2021', 'New', 'D', 10),
('10/1/2021', 'New', 'D', 10),
('10/1/2021', 'New', 'D', 10),
('10/1/2021', 'Old', 'D', 100),
('10/1/2021', 'Old', 'D', 70),
('11/1/2021', 'Old', 'A', 50)
;WITH Data AS (
SELECT
ts.InvoiceDate,
ts.Region,
SUM(ts.Quantity) AS QuantityAll,
SUM(CASE WHEN ts.Brand = 'New' THEN ts.Quantity ELSE 0 END) AS QuantityNew
FROM
#TotalSales ts
GROUP BY
ts.InvoiceDate,
ts.Region
)
SELECT
d.InvoiceDate,
d.Region,
d.QuantityAll,
d.QuantityNew,
d.QuantityAll - d.QuantityNew AS TheDifference
FROM
Data d
ORDER BY
d.InvoiceDate,
d.Region
I used a CTE so that we don't have to repeat the conditional SUM(CASE WHEN... for subtracting between QuantityNew and QuantityAll.
Output is:
InvoiceDate Region QuantityAll QuantityNew TheDifference
2021-10-01 A 100 40 60
2021-10-01 B 90 10 80
2021-10-01 C 150 50 100
2021-10-01 D 200 30 170
2021-11-01 A 50 0 50