SQL Group By and sum of other column - sql

Question

following is raw table
+--------------+---------------+----------+---------+-----------+
| CustomerName | InvoiceNumber | ItemRate | TaxRate | TaxAmount |
+--------------+---------------+----------+---------+-----------+
| A | 1 | 500 | 4% | 20 |
| B | 2 | 300 | 9% | 27 |
| B | 2 | 100 | 9% | 9 |
| B | 2 | 400 | 4% | 16 |
| C | 3 | 250 | 9% | 22.5 |
| C | 3 | 650 | 4% | 26 |
| D | 4 | 200 | 4% | 8 |
| D | 4 | 100 | 4% | 4 |
+--------------+---------------+----------+---------+-----------+
I want output like this:
+--------------+---------------+--------------+---------+-----------+
| CustomerName | InvoiceNumber | InvoiceTotal | TaxRate | TaxAmount |
+--------------+---------------+--------------+---------+-----------+
| A | 1 | 500 | 4% | 20 |
| B | 2 | 800 | 9% | 36 |
| B | 2 | 800 | 4% | 16 |
| C | 3 | 900 | 9% | 22.5 |
| C | 3 | 900 | 4% | 26 |
| D | 4 | 300 | 4% | 12 |
+--------------+---------------+--------------+---------+-----------+
I am having issue with sum of Invoice value when doing Group By.
I have to do group by with "TaxRate" to combine similar Taxes and along with it i want to include new column in result which shows Total for that perticular Invoice.
Invoice Total column should have sum of entire invoice, where as my current query is summing Total by tax group and not by entire invoice.
my query is:
Select CustomerName, InvoiceNumber, sum(itemrate) as InvoiceTotal, TaxRate, sum(TaxAmount)
from salestable group by customername,invoicenumber, Taxrate
Please help to resolve this.
Thanks

Answer 1

If I understand correctly, you want to sum itemrate over the invoice for each customer:
select CustomerName, InvoiceNumber,
sum(sum(itemrate)) over (partition by CustomerName, InvoiceNumber) as InvoiceTotal,
TaxRate,
sum(TaxAmount) as TaxAmount
from salestable
group by customername, invoicenumber, Taxrate

Answer 2

Try this-
WITH CTE AS
(
SELECT CustomerName,SUM(ItemRate) InvoiceTotal
FROM your_table
GROUP BY CustomerName
)
SELECT A.CustomerName,A.InvoiceNumber,B.InvoiceTotal,A.TaxRate,SUM(A.TaxAmount)
FROM your_table A
LEFT JOIN CTE B ON A.CustomerName = B.CustomerName
GROUP BY A.CustomerName,A.InvoiceNumber,B.InvoiceTotal,A.TaxRate
ORDER BY A.CustomerName,A.TaxRate DESC

Answer 3

Something like:
SELECT tab.CustomerName,
tab.InvoiceNumber,
it.InvoiceTotal,
tab.TaxRate,
SUM(tab.TaxAmount) AS TaxAmount
FROM tab
INNER JOIN (
SELECT InvoiceNumber, SUM(ItemRate) AS InvoiceTotal FROM tab GROUP BY InvoiceNumber
) it ON it.InvoiceNumber = tab.InvoiceNumber
GROUP BY tab.CustomerName, tab.InvoiceNumber, it.InvoiceTotal, tab.TaxRate
ORDER BY tab.CustomerName, tab.TaxRate DESC
See the associated fiddle.
Results:
A 1 500 4 20
B 2 800 9 36
B 2 800 4 16
C 3 900 9 22.5
C 3 900 4 26
D 4 300 4 12