Oracle trigger

ORACLE Trigger
Hasan Dwi Cahyono

Overviews
 Pengertian Trigger
 Schema Trigger
 Aplikasi Trigger
Perancangan Basis Data - Trigger2

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.

Pengertian Trigger (Lanjutan)
 Database triggers dapat digunakan dalam sebuah
table, schema, atau database.
 Cara memicunya ketika:
 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)

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 } ;

Schema Trigger: Create Trigger (Lanj.)

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 ]

Schema Trigger: DML Event Clause (Lanj.)

Schema Trigger: Referencing Clause
REFERENCING
{ OLD [ AS ] old
| NEW [ AS ] new
| PARENT [ AS ] parent }
[ OLD [ AS ] old
| NEW [ AS ] new
| PARENT [ AS ] parent ]...

Schema Trigger: Referencing Clause

Options: Event-nya
 AFTER atau bisa juga BEFORE.
 UPDATE ON bisa juga DELETE ON atau INSERT
ON.
 Dan UPDATE ON dapat juga UPDATE …OF… ON

Aplikasi Trigger (Buat tabel contoh)
CREATE TABLE Project_tab (
Prj_level NUMBER,
Projno NUMBER,
Resp_dept NUMBER
);
CREATE TABLE Emp_tab (
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
);
CREATE TABLE Dept_tab (
Deptno NUMBER(2) NOT NULL,
Dname VARCHAR2(14),
Loc VARCHAR2(13),
Mgr_no NUMBER,
Dept_type NUMBER
);

Contoh Trigger Pada Tabel
 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; /
 Lakukan Perintah:
UPDATE Emp_tab SET sal = sal + 500.00 WHERE deptno = 10;
 Apa yang terjadi?

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;

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;
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;
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;

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?

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;

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;

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)
/

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;
}
}

Latihan
 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)
);

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;
/

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;
/

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

Trigger:Membatalkan Perintah dengan Error
 Trigger dapat digunakan untuk melukan pengecekan contrain.
 Perintah-nya: RAISE_APPLICATION_ERROR.
 Perintah yang mengaktifkan Trigger (insert, update, atau delete) akan
dibatalkan.
 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;
/

Statement-Level Trigger
 Ketika operasi insert, update, atau delete operation
terjadi pada tabel emp, sebuah record akan
ditambahkan ke tabel empauditlog yang mencatat date,
user, dan action.
 Sebelumnya, buat tabel empauditlog table:
CREATE TABLE empauditlog (
audit_date DATE,
audit_user VARCHAR2(20),
audit_desc VARCHAR2(20)
);

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;
/

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 AUDIT_USER AUDIT_DESC
------------------ -------------------- --------------------
08-FEB-08 09:43:02 THOMO Added employee(s)
08-FEB-08 09:43:02 THOMO Deleted employee(s)
08-FEB-08 09:43:02 THOMO Updated employee(s)
08-FEB-08 09:43:02 THOMO Added employee(s)

Hal-hal Lain dalam Trigger
 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
WHERE name = 'PRICETRIG'
ORDER BY line;
 Menghapus Triggers
DROP TRIGGER <trigger_name>;
 Disabling atau Enabling Triggers
ALTER TRIGGER <trigger_name>
{DISABLE|ENABLE};
Harus
UpperCase?

Sumber:
 Oracle.com
 http://webhome.cs.uvic.ca/~thomo/courses/csc370S
pring2009/triggers.ppt

Oracle trigger

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