SQL SELECT Statment

Question

I'm trying to make a SELECT but I can´t test it on SQL management studio because it's always giving me errors.

I can´t find the error, any help is appreciated, thanks !

SELECT [Order].CustomOrderNumber, [Order].OrderTotal, [Order].OrderDiscount, [DiscountUsageHistory].DiscountID, [DiscountUsageHistory].OrderID, [Discount].ID, [Discount].Name 
FROM (([Order] , [Discount] , [DiscountUsageHistory] 
INNER JOIN [DiscountUsageHistory] ON [Order].CustomOrderNumber = [DiscountUsageHistory].OrderID) 
INNER JOIN [Discount] ON [DiscountUsageHistory].DiscountID = [Discount].ID)  
WHERE OrderDiscount > 0

Answer 1

Your query has a strange mixture of implicit joins and explicit joins. You should never use implicit joins, ever.

A correct query structure would be something like this:

SELECT [Order].CustomOrderNumber, 
       [Order].OrderTotal, 
       [Order].OrderDiscount, 
       [DiscountUsageHistory].DiscountID, 
       [DiscountUsageHistory].OrderID, 
       [Discount].ID, 
       [Discount].Name 
FROM [Order] 
INNER JOIN [DiscountUsageHistory] ON [Order].CustomOrderNumber = [DiscountUsageHistory].OrderID
INNER JOIN [Discount] ON [DiscountUsageHistory].DiscountID = [Discount].ID 
WHERE OrderDiscount > 0

Answer 2

If your relations are correct -

You had multiple tables linked to from .

The inner join makes those relations for you.

    SELECT [Order].CustomOrderNumber, [Order].OrderTotal, [Order].OrderDiscount, [DiscountUsageHistory].DiscountID, [DiscountUsageHistory].OrderID, [Discount].ID, [Discount].Name 
    FROM [Order] 
    INNER JOIN [DiscountUsageHistory] ON [Order].CustomOrderNumber = [DiscountUsageHistory].OrderID
    INNER JOIN [Discount] ON [DiscountUsageHistory].DiscountID = [Discount].ID 
    WHERE [Order].OrderDiscount > 0

Answer 3

Try:

SELECT 
    ORD.CustomOrderNumber, 
    ORD.OrderTotal, 
    ORD.OrderDiscount,
    DISUH.DiscountID,
    DISUH.OrderID,
    DIS.ID, 
    DIS.[Name]

FROM 
    [Order] AS ORD  
INNER JOIN 
    [DiscountUsageHistory] AS DISHU ON ORD.CustomOrderNumber = DISHU.OrderID
INNER JOIN 
    [Discount]  AS DIS ON DISHU.DiscountID = DIS.ID 
WHERE ORD.OrderDiscount > 0