Before trigger in sql server 2008

Question

I'm creating my first trigger in sql server 2008 . I have two tables, employee and employee_audit .

1. employee table have three fields empno ( auto increment ), first_name and last_name
2. employee_audit table have empno ( auto increment ) last_name.

I want to create trigger on employee and update its last name and before update this last name I want to store employee table's last_name in employees_audit table's last_name

create trigger before_employee_update
on employee
after update
as 
declare @last_name varchar(20)
select @last_name = i. last_name from inserted i;
Begin 
Insert into employees_audit(last_name) 
values(@last_name);
end;

what I have to write instead of "after" cz I first want to store the old last_name value in employees_audit table and then want to update last_name value in employee

and before is not recognized trigger in sql server

Answer 1

Trigger to insert last name in employee_audit table Instead of updating the record in employee table.

Use Instead of update trigger to do this. below is the query please refer it:

Create trigger InsOf_update_employee on employee
Instead of update
as 
declare @last_name varchar(20)
select @last_name = i. last_name from inserted i;
if update(last_name)
  begin
    insert into employees_audit (last_name) values (@last_name);
  end
print 'Successfully fired the before update trigger'
Go 

then try to update the employee table's last name field of any record. example:

update employee set last_name='xyz' where empno=2;

It will insert the record in employee_audit table during updating the employee table.