Practice Activity - Creating a rolling total over the last 3 months in SQL Server

If you are in March, how can you total January, February and March's figures in SQL Server?
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You can create a running total using partition functions. However, what if you only wanted the running total to be over the last 3 months?
There are many ways of doing this. In this video, we will look at using a correlated query, and using a self-join.
We will also be looking at the DATEDIFF and DATEFROMPARTS functions.
Here is the code that we will be using to create the tables, if you want to use this as a Practice Activity:
DROP TABLE IF EXISTS Invoices;
CREATE TABLE Invoices
(InvoiceDate date,
InvoiceAmount int);
INSERT INTO Invoices
VALUES
('2022-12-01', 1), ('2023-02-01', 1), ('2023-02-15', 1),
('2023-03-01', 3), ('2023-04-01', 2), ('2023-04-15', 2),
('2023-05-01', 5), ('2023-06-01', 3), ('2023-06-15', 3), ('2023-08-01', 8);