Question

I’ve been using SQLPLUS lately and one of my tasks was to display a set of values from two tables (stocks, orderitems). I have done this part, but I am stuck on the last part of the question which states: “including the stocks that no order has been placed on them so far”.

Here is the statement:

`select Stocks.StockNo, Stocks.Description, OrderItems.QtyOrd
 from Stocks INNER JOIN OrderItems
 ON Stocks.StockNo = OrderItems.StockNo;`

and I have gotten the correct results for this part, but the second part is eluding me, as the curernt statement doesn’t display the 0 values for QtyOrd.
Any help would be appreciated.

Answer 1

You likely want to use a LEFT OUTER JOIN otherwise the INNER JOIN will exclude Stocks which don’t have any Orders. You might also consider grouping by Stock, in order to SUM the overall quantities for each stock?

SELECT  Stocks.StockNo, Stocks.Description, SUM(OrderItems.QtyOrd) AS QtyOrd
FROM  Stocks 
    LEFT OUTER JOIN OrderItems
         ON Stocks.StockNo = OrderItems.StockNo
GROUP BY Stocks.StockNo, Stocks.Description;