MySQL - Using subqueries on join and from - mysql

Question

I am trying to return the CustomerID, CompanyName, OrderID, and subtotals for each customer for all order the subtotal amounts that are higher than the customer’s average subtotal amount. These are the tables I am using and the query below. I am unsure if the values I return are correct and was hoping someone could help me understand if they are or not based on my query. Thanks in advance.
Orders
Columns
OrderID
CustomerID
EmployeeID
OrderDate
RequiredDate
OrderDetails
Columns
OrderID
ProductID
UnitPrice
Quantity
Products
Columns
ProductID
ProductName
QuantityPerUnit
UnitPrice
Customers
Columns
CustomerID
CompanyName
ContactName
Country
SELECT A.CustomerID, A.CompanyName, A.Subtotal, A.OrderID, AVGSubtotal
FROM (
SELECT
C.CustomerID,
C.CompanyName,
(D.UnitPrice * P.QuantityPerUnit) AS Subtotal,
D.OrderID
FROM Customers C
JOIN Orders O ON C.CustomerID = O.CustomerID
JOIN OrderDetails D ON D.OrderID = O.OrderID
JOIN Products P ON P.ProductID = D.ProductID
GROUP BY
D.OrderID, C.CustomerID
) A
JOIN (
SELECT
S.CustomerID, S.CompanyName, AVG(S.Subtotal) as AVGSubtotal
FROM (
SELECT
C.CustomerID,
C.CompanyName,
(D.UnitPrice * P.QuantityPerUnit) AS Subtotal
FROM Customers C
JOIN Orders O ON C.CustomerID = O.CustomerID
JOIN OrderDetails D ON D.OrderID = O.OrderID
JOIN Products P ON P.ProductID = D.ProductID
GROUP BY
D.OrderID, C.CustomerID
) S
GROUP BY
S.CustomerID
) B ON A.CustomerID = B.CustomerID
WHERE
A.CustomerID = B.CustomerID AND
A.Subtotal > B.AVGSubtotal
ORDER BY
A.CustomerID, A.CompanyName
;

Answer 1

select
c2.customerID,
c2.CompanyName,
c2.AVGSubtotal
o2.OrderID,
o2.UnitPrice * o2.Quantity as subtotal
from (
select
c.CustomerID,
c.CompanyName,
sum(o.UnitPrice * o.Quantity)/count(*) as AVGSubtotal
from
Customers c
inner join Orders o on (o.CustomerID = c.CustomerID)
inner join OrderDetails od on (od.OrderID = c.OrderID)
group by
o.CustomerID
) as c2
inner join Orders o2 on (o2.CustomerID = c2.CustomerID)
where o2.UnitPrice * o2.Quantity > c2.AVGSubtotal