This sample show ways to optimize PHP code. The samples need the
mylibrary database. (The password data is read from ../password.php.)

- create_categories_test.php makes a backup of the categories
  table and then creates a new categories table with
  random data.

- show_categories_list.php creates a drop-down list for the 
  categories table using three different algorithms.

- remove_categories_test.php deletes the categories test table
  an restore the original categories table.
