The document provides an overview of database triggers in Oracle, defining them as PL/SQL statements activated by specific DML or system events on a database table. It details trigger types, including application and database triggers, and describes their timing (before or after events). Additionally, it outlines how to create, manage, and grant permissions for triggers with examples for better understanding.

1. Oracle Database
Trigger
Eryk Budi Pratama – Dimas Aryo Anggoro
Advanced Database Lab
Informatics Engineering –Bakrie University

2. Definition
• Trigger is a series of PL/SQL statements attached
to a database table that execute whenever a
triggering event (select, update, insert, delete)
occurs.
• Unlike stored procedures and functions, they
not explicitly called, but they are activated when
a triggering event occurs.
• Main purpose is to implement the complex
integrity constraints that can’t be done with the
CREATE TABLE or ALTER TABLE command.

3. Trigger Types
• Application Trigger
Trigger will be activated if there is an event on
certain application
• Database Trigger
Trigger will be activated if there is a data event
(DML Operation – Insert, Update, Delete) or
system event (logon or shutdown) on a schema
or database

4. Trigger Timing
• BEFORE
where a trigger will be activated before DML process on
table occur
• AFTER
where a trigger will be activated after DML process on
table occur
• INSTEAD OF
Trigger that just functionate on VIEW and usually used to
update data on complex view

5. Syntax
CREATE [OR REPLACE]
TRIGGER trigger_name
BEFORE (or AFTER)
INSERT OR UPDATE [OF COLUMNS] OR DELETE
ON tablename
[FOR EACH ROW [WHEN (condition)]]
BEGIN
...
END;

6. Example

7. Sample Table
CREATE TABLE PERSON (
ID INT,
NAME VARCHAR(30),
DOB DATE,
PRIMARY KEY(ID)
);

8. Before Insert Trigger
CREATE OR REPLACE
TRIGGER PERSON_INSERT_BEFORE
BEFORE
INSERT
ON PERSON
FOR EACH ROW
BEGIN
DBMS_OUTPUT.PUT_LINE(’BEFORE INSERT OF ’ ||
:NEW.NAME);
END;

9. (cont.)
• The single INSERT statement fires the trigger. When we
run it, we get the print out of ’BEFORE INSERT OF JOHN
DOE’.
SQL> INSERT INTO PERSON(ID,NAME,DOB) VALUES (1, ’ANI’
,SYSDATE);
BEFORE INSERT OF ANI
1 row created.

10. After Insert Trigger
CREATE OR REPLACE
TRIGGER PERSON_INSERT_AFTER
AFTER
INSERT
ON PERSON
FOR EACH ROW
BEGIN
DBMS_OUTPUT.PUT_LINE(’AFTER INSERT OF ’ || :NEW.NAME);
END;

11. (cont.)
SQL> INSERT INTO PERSON(ID,NAME,DOB) VALUES (2, ’BUDI’
,SYSDATE);
BEFORE INSERT OF BUDI
AFTER INSERT OF BUDI
1 row created.

12. Before Update Trigger
CREATE OR REPLACE
TRIGGER PERSON_UPDATE_S_BEFORE
BEFORE UPDATE
ON PERSON
BEGIN
DBMS_OUTPUT.PUT_LINE(’BEFORE UPDATING SOME
PERSON(S)’);
END;

13. (cont.)
SQL> UPDATE PERSON SET DOB = SYSDATE;
BEFORE UPDATING SOME PERSON(S)
2 rows updated

14. Managing Trigger
• Enable Trigger
ALTER TRIGGER trigger_name ENABLE
• Disable Trigger
ALTER TRIGGER trigger_name DISABLE
• Enable or Disable All Trigger
ALTER TABLE table_name DISABLE | ENABLE ALL TRIGGERS
• Delete TRIGGER
DROP TRIGGER nama_trigger

15. Permissions
Just like with procedures and functions, creating triggers
requires certain privileges which are not part of the default
privilege set.
GRANT CREATE TRIGGER TO <username>;

16. Q&A