Problem 2 Write a stored procedure to finish the following function: according to the inputted department number, output the average salary of all employees of this t. Problem3 Write a stored procedure to change the salary by the input employee number: if the employee's salary is greater than 100, increase 100 on the basis of the original value; if the salary is equal to O or null then it is set to 200. Problem 4 Write a stored procedure to change the salary by the input employee number: if the employee's salary is greater than 100, increase 100 on the basis of the original value; if the salary is equal to 0 or null then it is set to 200.(need to use cursor in E5)