Triggers allow the DBMS to audit changes to the database as well as ensure the integrity of its data. Figure 1(Below) 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)

In your responses to other students, consider their logic for the trigger and how it compares to your own logic process.

Fig 1.

Fog

create or replace trigger ADDENROLL after insert on revenroll for each row begin update revclass set currentenrol1-currentenrol1+1 where revclass.classnumber-:new.classnumber exception when no_data_found then DBMS_OUTPUT. PUT LINE('No data found'); when others then DBMS_OUTPUT. PUT_LINE('ErrorSQLERRM) end