Create a package which contains function to ask the user to enter the student’s marks and determine the GRADE according to the following criteria. >90 A >80AND <90 B >70AND <80 C >60 AND<70 D <60 F

Create a trigger which will work before deletion in employee table and print a message “Deletion started”

Create a procedure or function to calculate electricity bill as per the following criteria:   For first 100 units: Rs. 5 per unit   For 101-150 units: Rs. 7 per unit   For 151-300 units: Rs. 7.50 per unit   For 301 onward units: Rs. 8 per unit