81. Write a query to display the highest book cost in the system (Figure P7.81)

83. Write a query to display the number of different patrons who have ever checked out a book (Figure P7.83).

85. Write a query to display the author ID and the number of books written by that author. Sort the results in descending order by number of books, then in ascending order by author ID (Figure P7.85).

87. Write a query to display the patron ID, book number, and days kept for each check[1]out. "Days Kept" is the difference from the date on which the book is returned to the date it was checked out. Sort the results by days kept in descending order, then by patron ID, and then by book number (Figure P7.87). (68 rows)

88. Write a query to display the book number, title with year, and subject for each book. Sort the results by the book number (Figure P7.89). (20 rows)

91. Write a query to display the author ID, book number, title, and subject for each book. Sort the results by book number and then author ID (Figure P7.91). (25 rows

93. Write a query to display the patron ID, book number, patron first name and last name, and book title for all currently checked out books. (Remember to use the redundant relationship described in the assignment instructions for current check[1]outs.) Sort the output by patron last name and book title (Figure P7.93).

95. Write a query to display the book number and the number of times each book has been checked out. Do not include books that have never been checked out. Sort the results by the number of times checked out in descending order and then by book number in descending order (Figure P7.95).

97. Write a query to display the book number, title, author last name, author first name, patron ID, last name, and patron type for all books currently checked out to a patron. Sort the results by book title (Figure P7.97).

99. Write a query to display the book number, title, and number of times each book has been checked out. Limit the results to books that have been checked out more than five times. Sort the results in descending order by the number of times checked out and then by title (Figure P7.99)