The following needs to be performed in SQL and and PL/SQL not MYSQL

Create audit table which will be populated each time a books retail price or cost is changed. The name, what fields you include in the audit table and it's intended use are for you to determine.

Create trigger to populate the audit table described above

Create function which returns the average retail price of all books in the books table

Create procedure which utilizes a cursor to update the retail price of all books in the books by a given percentage