以下为引用的内容: activity.lst SQL> SQL> select Name, Title, CheckoutDate, ReturnedDate, 2 ReturnedDate-CheckoutDate as DaysOut /*Count Days*/ 3 from BOOKSHELF_CHECKOUT 4 order by Name,CheckoutDate; Mon Aug 28 page 1 Checkout Log for 1/1/02-3/31/02 Days NAME TITLE CHECKOUTDATE RETURNEDDATE Out ------------ -------- ------------ ------------ ---- DORAH TALBOT EITHER/OR 02-JAN-02 10-JAN-02 8.00 POLAR EXPRESS 01-FEB-02 15-FEB-02 14.00 GOOD DOG, CARL 01-FEB-02 15-FEB-02 14.00 MY LEDGER 15-FEB-02 03-MAR-02 16.00 ******************** ------- avg 13.00 EMILY TALBOT ANNE OF GREEN GABLES 02-JAN-02 20-JAN-02 18.00 MIDNIGHT MAGIC 20-JAN-02 03-FEB-02 14.00 HARRY POTTER AND 03-FEB-02 14-FEB-02 11.00 THE GOBLET OF FIRE ******************** ------- avg 14.33 FRED FULLER JOHN ADAMS 01-FEB-02 01-MAR-02 28.00 TRUMAN 01-MAR-02 20-MAR-02 19.00 ******************** ------- avg 23.50 GERHARDT KENTGEN WONDERFUL LIFE 02-JAN-02 02-FEB-02 31.00 MIDNIGHT MAGIC 05-FEB-02 10-FEB-02 5.00 THE MISMEASURE OF 13-FEB-02 05-MAR-02 20.00 MAN ******************** ------- avg 18.67 JED HOPKINS INNUMERACY 01-JAN-02 22-JAN-02 21.00 TO KILL A 15-FEB-02 01-MAR-02 14.00 MOCKINGBIRD