Q$1.(20$ points$)$ statement level Trigger. This question is based on table EMP.

Recall that generally, there will be four steps for completing trigger related questions.

The first step, we will create a log table called Emp$\_$Log as below:In the second step, you will create a statement level trigger named Emp$\_$Update on table Emp. Whenever there is a command of update on the table Emp, the trigger will be fired, and one record will be added into the table Emp$\_$log$.$ Generally, the Updated$\_$Date value will use the function SYSDATE, the Updated$\_$by will be the current login name "User". You are free to define the string for action here.

Step third: after having successfully compiled the trigger, your program will run one Update command to test the trigger:

Update Emp set sal $=$ sal $*1\mathrm{.}1$ where deptno $=20$ ;

In the fourth step, you need to check the contents of Empl$\_$log table, that will display the new records in the log table.

It will be a good practice, to remember to rollback after you get the display of the results:

Rollback;

DROP TRIGGER Emp$\_$Update;

$**$ You may notice that the "rollback" will cancel the update command on table EMP, also it will delete the correspondent record in the Emp$\_$log table $($ you do: Select $*$ from Emp$\_$log again after the roll back; you will see there is no record in that $log$ table$).$

An advanced question: if you would like to keep the record in Emp$\_$log file, even the triggering event $($update$)$ is cancelled, what you should do$?($Refer to Note$7$c$\_$Transactions, section $3,$ page $6-8).$