Question

In my query below, i am trying to join one result set to another using the customerNumber identifier. I want to find each customer’s amount ordered and the amount paid. The sql does not execute with no help from Navicat Client

SELECT DISTINCT tabl1.customerNumber, 
                tabl1.amountOrdered, tabl2.amountPaid
FROM
(
     SELECT Distinct c.customerNumber, o.orderNumber, 
             SUM(od.quantityOrdered * od.priceEach) amountOrdered
     FROM ClassicModels.Customers c
     INNER JOIN ClassicModels.Orders o 
                ON c.customerNumber = o.customerNumber
     INNER JOIN ClassicModels.OrderDetails od 
                ON o.orderNumber = od.orderNumber
     GROUP BY od.orderNumber
     ORDER BY c.customerNumber
) tabl1
INNER JOIN 
(
     SELECT DISTINCT c.customerNumber, p.amount amountPaid
     FROM ClassicModels.Customers c 
     INNER JOIN ClassicModels.Payments p 
                ON c.customerNumber = p.customerNumber
 ) tabl2 ON tabl1.customerNumber = tabl2.customerNumber

Answer 1

If you want to select each customer’s amount ordered and amount paid, this much simpler query should work:

SELECT o.customerNumber as customerNumber, 
    SUM(od.quantityOrdered * od.priceEach) as amountOrdered, 
    SUM(p.amount) as amountPaid
FROM ClassicModels.Orders o
INNER JOIN ClassicModels.OrderDetails od
    ON o.OrderNumber = od.OrderNumber
LEFT JOIN ClassicModels.Payments p
    ON p.customerNumber = o.customerNumber
GROUP BY o.customerNumber