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ORACLE Trigger
Hasan Dwi Cahyono
Overviews
Pengertian Trigger
Schema Trigger
Aplikasi Trigger
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Perancangan Basis Data - Trigger
Pengertian Trigger
Database triggers adalah prosedur yang tersimpan dalam
database dan di aktifkan ketika kondisi tertentu terjadi
Dapat digunakan untuk menambah kapabilitas agar
database mampu dikostumasi secara sistematis.
Sebagai contoh, membuat Trigger yang dapat membatasi
perintah DML tertentu pada sebuah tabel dan mengijinkan
perintah tertentu pada waktu tertentu juga.
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Perancangan Basis Data - Trigger
Pengertian Trigger (Lanjutan)
Database triggers dapat digunakan dalam sebuah table,
schema, atau database.
Cara memicunya ketika:
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Perintah DML dieksekusi (INSERT, UPDATE, DELETE)
terhadap tabel tertentu.
DDL tertentu dieksekusi (contohnya:
ALTER, CREATE, DROP) pada sebuah objek pada database
atau schema.
Event tertentu terjadi pada database
(contohnya: STARTUP, SHUTDOWN, SERVERERROR)
Perancangan Basis Data - Trigger
Schema Trigger: Create Trigger
CREATE [ OR REPLACE ] TRIGGER [ schema. ]trigger
{ BEFORE | AFTER | INSTEAD OF }
{ dml_event_clause
| { ddl_event [ OR ddl_event ]...
| database_event [ OR database_event ]...
} ON { [ schema. ]SCHEMA
| DATABASE
}
}
[ WHEN (condition) ]
{ pl/sql_block | call_procedure_statement } ;
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Perancangan Basis Data - Trigger
Schema Trigger: Create Trigger (Lanj.)
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Perancangan Basis Data - Trigger
Schema Trigger: DML Event Clause
{ DELETE | INSERT | UPDATE
[ OF column [, column ]... ]
}
[ OR { DELETE | INSERT | UPDATE
[ OF column [, column]... ]
}
]...
ON { [ schema. ]table
| [ NESTED TABLE nested_table_column OF ]
[ schema. ] view
}
[ referencing_clause ]
[ FOR EACH ROW ]
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Perancangan Basis Data - Trigger
Schema Trigger: DML Event Clause (Lanj.)
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Perancangan Basis Data - Trigger
Schema Trigger: Referencing Clause
REFERENCING
{ OLD [ AS ] old
| NEW [ AS ] new
| PARENT [ AS ] parent }
[ OLD [ AS ] old
| NEW [ AS ] new
| PARENT [ AS ] parent ]...
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Perancangan Basis Data - Trigger
Schema Trigger: Referencing Clause
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Perancangan Basis Data - Trigger
Options: Event-nya
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AFTER atau bisa juga BEFORE.
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UPDATE ON bisa juga DELETE ON atau INSERT
ON.
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Dan UPDATE ON dapat juga UPDATE …OF… ON
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Perancangan Basis Data - Trigger
Aplikasi Trigger (Buat tabel contoh)
CREATE TABLE Dept_tab (
CREATE TABLE Project_tab (
Prj_level NUMBER,
Deptno NUMBER(2) NOT NULL,
Projno NUMBER,
Dname VARCHAR2(14),
Resp_dept NUMBER
Loc VARCHAR2(13),
);
Mgr_no NUMBER,
CREATE TABLE Emp_tab (
Dept_type NUMBER
);
Empno NUMBER NOT NULL,
Ename VARCHAR2(10),
Job VARCHAR2(9),
Mgr NUMBER(4),
Hiredate DATE,
Sal NUMBER(7,2),
Comm NUMBER(7,2),
Deptno NUMBER(2) NOT NULL
);
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Perancangan Basis Data - Trigger
Contoh Trigger Pada Tabel
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Terjadi Ketika Insert, Update, dan Delete
CREATE OR REPLACE TRIGGER Print_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON Emp_tab
FOR EACH ROW
WHEN (new.Empno > 0)
DECLARE
sal_diff number;
BEGIN
sal_diff := :new.sal - :old.sal;
dbms_output.put('Old salary: ' || :old.sal);
dbms_output.put(' New salary: ' || :new.sal);
dbms_output.put_line(' Difference ' || sal_diff);
END; /
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Lakukan Perintah:
UPDATE Emp_tab SET sal = sal + 500.00 WHERE deptno = 10;
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Apa yang terjadi?
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Perancangan Basis Data - Trigger
Contoh Trigger Pada View
CREATE OR REPLACE VIEW manager_info AS
SELECT e.ename, e.empno, d.dept_type,
d.deptno, p.prj_level, p.projno
FROM Emp_tab e, Dept_tab d, Project_tab p
WHERE e.empno = d.mgr_no
AND d.deptno = p.resp_dept;
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Perancangan Basis Data - Trigger
Contoh Trigger Pada View (Lanjutan)
CREATE OR REPLACE TRIGGER
manager_info_insert
INSTEAD OF INSERT ON manager_info
REFERENCING NEW AS n
-- new manager information
FOR EACH ROW
DECLARE
rowcnt number;
BEGIN
SELECT COUNT(*) INTO rowcnt
FROM Emp_tab WHERE empno = :n.empno;
IF rowcnt = 0 THEN
INSERT INTO Emp_tab (empno,ename)
VALUES (:n.empno, :n.ename);
ELSE
UPDATE Emp_tab
SET Emp_tab.ename = :n.ename
WHERE Emp_tab.empno = :n.empno;
END IF;
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SELECT COUNT(*) INTO rowcnt
FROM Dept_tab WHERE deptno = :n.deptno;
IF rowcnt = 0 THEN
INSERT INTO Dept_tab (deptno, dept_type)
VALUES(:n.deptno, :n.dept_type);
ELSE
UPDATE Dept_tab
SET Dept_tab.dept_type = :n.dept_type
WHERE Dept_tab.deptno = :n.deptno;
END IF;
SELECT COUNT(*) INTO rowcnt
FROM Project_tab
WHERE Project_tab.projno = :n.projno;
IF rowcnt = 0 THEN
INSERT INTO Project_tab (projno, prj_level)
VALUES(:n.projno, :n.prj_level);
ELSE
UPDATE Project_tab
SET Project_tab.prj_level = :n.prj_level
WHERE Project_tab.projno = :n.projno;
END IF;
END;
Perancangan Basis Data - Trigger
Contoh Trigger Pada View (Lanjutan)
Lakukan Perintah:
INSERT INTO manager_info
(ename, empno, dept_type, deptno,
prj_level, projno)
VALUES(‘Andi’, 101, 1, 1, 1,1);
 Apa yang terjadi?
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Perancangan Basis Data - Trigger
Firing Triggers Sekali atau Berkali-kali
(FOR EACH ROW Option)
CREATE TABLE Emp_log (
Emp_id NUMBER,
Log_date DATE,
New_salary NUMBER,
Action VARCHAR2(20)
);
CREATE OR REPLACE TRIGGER
Log_salary_increase
AFTER UPDATE ON Emp_tab
FOR EACH ROW
WHEN (new.Sal > 1000)
BEGIN
INSERT INTO Emp_log
(Emp_id, Log_date,
New_salary, Action)
VALUES (:new.Empno,
SYSDATE, :new.SAL,
'NEW SAL');
END;
Lakukan perintah:
UPDATE Emp_tab SET Sal = Sal + 1000.0 WHERE Deptno = 20;
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Perancangan Basis Data - Trigger
Trigger Ini Hanya Dijalankan Sekali
CREATE OR REPLACE TRIGGER Log_emp_update
AFTER UPDATE ON Emp_tab
BEGIN
INSERT INTO Emp_log (Log_date, Action)
VALUES (SYSDATE,
'Emp_tab COMMISSIONS CHANGED');
END;
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Perancangan Basis Data - Trigger
Memanggil Java Procedure dari Trigger
CREATE OR REPLACE PROCEDURE Before_delete (Id IN NUMBER, Ename
VARCHAR2)
IS language Java
name 'thjvTriggers.beforeDelete (oracle.sql.NUMBER,
oracle.sql.CHAR)';
CREATE OR REPLACE TRIGGER Pre_del_trigger
BEFORE DELETE ON Tab
FOR EACH ROW
CALL Before_delete (:old.Id, :old.Ename)
/
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Perancangan Basis Data - Trigger
thjvTriggers.java
import java.sql.*
import java.io.*
import oracle.sql.*
import oracle.oracore.*
public class thjvTriggers {
public state void beforeDelete (NUMBER old_id, CHAR old_name)
Throws SQLException, CoreException
{
Connection conn = JDBCConnection.defaultConnection();
Statement stmt = conn.CreateStatement();
String sql = “insert into logtab values (“ +
old_id.intValue() + ", '“ +
old_ename.toString() + ", BEFORE DELETE');
stmt.executeUpdate (sql);
stmt.close();
return;
}
}
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Perancangan Basis Data - Trigger
Latihan
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Menggunakan tabel Penjual(nama, minuman, harga) dan sebuah relasi
unary, simpan daftar penjual yang menaikkan harga sebesar Rp.1000.
 Misal relasi Unary-nya kepada: KumpulanPenjual(nama).
CREATE TABLE Penjual(
minuman VARCHAR(10),
nama
VARCHAR(13),
harga FLOAT
);
CREATE TABLE KumpulanPenjual(
nama VARCHAR(13)
);
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Perancangan Basis Data - Trigger
Trigger
CREATE OR REPLACE TRIGGER PriceTrig
AFTER UPDATE OF price ON Penjual
FOR EACH ROW
WHEN (new.harga > old.harga + 1000)
BEGIN
INSERT INTO KumpulanPenjual
VALUES(:new.nama);
END;
/
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Perancangan Basis Data - Trigger
Contoh Lainnya:
CREATE TABLE emp (
empno INT,
ename VARCHAR(30),
deptno INT,
sal FLOAT,
comm FLOAT
);
CREATE OR REPLACE TRIGGER emp_comm_trig
BEFORE INSERT ON emp
FOR EACH ROW
BEGIN
IF :NEW.deptno = 30 THEN
:NEW.comm := :NEW.sal * .4;
END IF;
END;
/
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Perancangan Basis Data - Trigger
Latihan:
INSERT INTO emp VALUES (9005,'ROBERS',30,
3000,NULL);
INSERT INTO emp VALUES (9006,'ALLEN',30, 4500,NULL);
SELECT * FROM emp WHERE empno IN (9005, 9006);
EMPNO ENAME DEPTNO
SAL
COMM
----------------------------------9005 ROBERS
30
3000 1200
9006 ALLEN
30
4500 1800
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Perancangan Basis Data - Trigger
Trigger:Membatalkan Perintah dengan Error
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Trigger dapat digunakan untuk melukan pengecekan contrain.
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Perintah-nya: RAISE_APPLICATION_ERROR.
Perintah yang mengaktifkan Trigger (insert, update, atau delete) akan
dibatalkan.
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Contohnya, perintah berikut ini memaksa nilai input harus Person.age >= 0:
CREATE TABLE Person (age INT);
CREATE TRIGGER PersonCheckAge
AFTER INSERT OR UPDATE OF age ON Person
FOR EACH ROW
BEGIN
IF (:new.age < 0) THEN
RAISE_APPLICATION_ERROR(-20000, 'no negative age allowed');
END IF;
END;
/
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Perancangan Basis Data - Trigger
Statement-Level Trigger
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Ketika operasi insert, update, atau delete operation terjadi
pada tabel emp, sebuah record akan ditambahkan ke tabel
empauditlog yang mencatat date, user, dan action.
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Sebelumnya, buat tabel empauditlog table:
CREATE TABLE empauditlog (
audit_date
DATE,
audit_user
VARCHAR2(20),
audit_desc
VARCHAR2(20)
);
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Perancangan Basis Data - Trigger
Trigger
CREATE OR REPLACE TRIGGER emp_audit_trig
AFTER INSERT OR UPDATE OR DELETE ON emp
DECLARE
v_action
VARCHAR2(20);
BEGIN
IF INSERTING THEN
v_action := 'Added employee(s)';
ELSEIF UPDATING THEN
v_action := 'Updated employee(s)';
ELSEIF DELETING THEN
v_action := 'Deleted employee(s)';
END IF;
INSERT INTO empauditlog
VALUES (SYSDATE, USER, v_action);
END;
/
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Perancangan Basis Data - Trigger
Sekarang jalankan:
INSERT INTO emp (empno, ename, deptno) VALUES (9001,'SMITH',50);
INSERT INTO emp (empno, ename, deptno) VALUES (9002,'JONES',50);
UPDATE emp
SET ename = 'SMITH BROWN'
WHERE empno=9001;
DELETE FROM emp WHERE empno IN (9001, 9002);
SELECT TO_CHAR(AUDIT_DATE,'DD-MON-YY HH24:MI:SS') AS "AUDIT DATE",
audit_user, audit_desc
FROM empauditlog
ORDER BY 1 ASC;
AUDIT DATE
-----------------08-FEB-08 09:43:02
08-FEB-08 09:43:02
08-FEB-08 09:43:02
08-FEB-08 09:43:02
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AUDIT_USER
-------------------THOMO
THOMO
THOMO
THOMO
AUDIT_DESC
-------------------Added employee(s)
Deleted employee(s)
Updated employee(s)
Added employee(s)
Perancangan Basis Data - Trigger
Hal-hal Lain dalam Trigger
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Viewing Defined Triggers
 Untuk melihat Trigger yang tersimpan, gunakan perintah:
SELECT *
FROM USER_TRIGGERS[/DBA_TRIGGERS ]
WHERE TABLE_NAME = ‘MY_TABLE’;
 Melihat isi (code) Trigger:
SELECT text
FROM user_source
Harus
WHERE name = 'PRICETRIG'
UpperCase?
ORDER BY line;
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Menghapus Triggers
DROP TRIGGER <trigger_name>;
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Disabling atau Enabling Triggers
ALTER TRIGGER <trigger_name>
{DISABLE|ENABLE};
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Perancangan Basis Data - Trigger
Sumber:
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Oracle.com
http://webhome.cs.uvic.ca/~thomo/courses/csc370Spring2
009/triggers.ppt
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Perancangan Basis Data - Trigger