Triggers allow the DBMS to audit changes to the database as well as ensure the integrity of its data. Figure 5.6(B) in your text is an example of a trigger designed to update the total number of students enrolled in a class whenever another student enrolls.

For the Employee table below, write a trigger that will call a stored procedure which will create an audit trail that will track all updates to the salary field. The audit records will be written into the SalaryAudit table, as seen below. Explain the logic of each step of your trigger.

Employee (EmpID, lastName, firstName, department, salary, dateHired)

SalaryAudit (Date_of_update, EmpID, oldsalary, newsalary)