Question

Using the BOOK_ORDER, ORDER_ITEMS, and BOOKS tables, create a query using an OUTER JOIN operation that will list the book title, order date, and order number for all books in the BOOKS table. Order your output in descending order by ORDER_ITEMS.BOOKID. There are three books that have never been ordered which should show up at the top of your listing.

I wrote this query:-

SELECT B.TITLE, BO.ORDERDATE, ORD.ORDERID FROM BOOKS B, BOOK_ORDER BO, ORDERITEMS ORD
WHERE B.BOOKID = ORD.BOOKID
AND BO.ORDERID = ORD.ORDERID(+)
ORDER BY ORD.ORDERID DESC

I am getting the results but confused about this following part of the question:-

“There are three books that have never been ordered which should show up at the top of your listing.”

I am guessing this mean I need to display those Books that have Orderdate and OrderId as NULL or blank. But how do I get those rows on top of the result set? What should I change in the query that I have written?

This is the BOOKS table:-

Name                                      Null?    Type
----------------------------------------- -------- ---------------
BOOKID                                    NOT NULL NUMBER(15)
ISBN                                               VARCHAR2(10)
TITLE                                              VARCHAR2(30)
PUBDATE                                            DATE
PUBID                                              NUMBER(2)
COST                                               NUMBER(5,2)
RETAIL                                             NUMBER(5,2)
CATEGORY                                           VARCHAR2(12)

This is ORDER_ITEMS table:-

 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------
 ORDERID                                   NOT NULL NUMBER(4)
 ITEMNUM                                   NOT NULL NUMBER(2)
 BOOKID                                    NOT NULL NUMBER(15)
 QUANTITY                                           NUMBER(3)

and here is BOOK_ORDER table structure:-

 Name                                      Null?    Type
 ----------------------------------------- -------- --------------
 ORDERID                                   NOT NULL NUMBER(4)
 CUSTOMERID                                         NUMBER(4)
 ORDERDATE                                          DATE
 SHIPDATE                                           DATE
 SHIPSTREET                                         VARCHAR2(20)
 SHIPCITY                                           VARCHAR2(20)
 SHIPSTATE                                          VARCHAR2(2)
 SHIPZIP                                            VARCHAR2(5)

Answer 1

try this:

SELECT B.TITLE,
       BO.ORDERDATE,
       ORD.ORDERID
FROM BOOKS B,
     BOOK_ORDER BO,
     ORDER_ITEMS ORD
WHERE B.BOOKID = ORD.BOOKID(+)
  AND BO.ORDERID(+) = ORD.ORDERID
ORDER BY ORD.ORDERID DESC

By the way, IMHO, it’s better not to use the (+) operator but the ANSI JOIN keywords:

SELECT B.TITLE,
       BO.ORDERDATE,
       ORD.ORDERID
FROM BOOKS B
LEFT OUTER JOIN ORDER_ITEMS ORD ON B.BOOKID = ORD.BOOKID
FULL OUTER JOIN  BOOK_ORDER BO ON BO.ORDERID = ORD.ORDERID
ORDER BY ORD.ORDERID DESC

here is a fiddle