Fire a trigger before an update of the table : Before Event Trigger « Trigger « Oracle PL/SQL Tutorial

Oracle PL/SQL Tutorial
1. Introduction
2. Query Select
3. Set
4. Insert Update Delete
5. Sequences
6. Table
7. Table Joins
8. View
9. Index
10. SQL Data Types
11. Character String Functions
12. Aggregate Functions
13. Date Timestamp Functions
14. Numerical Math Functions
15. Conversion Functions
16. Analytical Functions
17. Miscellaneous Functions
18. Regular Expressions Functions
19. Statistical Functions
20. Linear Regression Functions
21. PL SQL Data Types
22. PL SQL Statements
23. PL SQL Operators
24. PL SQL Programming
25. Cursor
26. Collections
27. Function Procedure Packages
28. Trigger
29. SQL PLUS Session Environment
30. System Tables Data Dictionary
31. System Packages
32. Object Oriented
33. XML
34. Large Objects
35. Transaction
36. User Privilege
Java
Java Tutorial
Java Source Code / Java Documentation
Java Open Source
Jar File Download
Java Articles
Java Products
Java by API
Photoshop Tutorials
Maya Tutorials
Flash Tutorials
3ds-Max Tutorials
Illustrator Tutorials
GIMP Tutorials
C# / C Sharp
C# / CSharp Tutorial
C# / CSharp Open Source
ASP.Net
ASP.NET Tutorial
JavaScript DHTML
JavaScript Tutorial
JavaScript Reference
HTML / CSS
HTML CSS Reference
C / ANSI-C
C Tutorial
C++
C++ Tutorial
Ruby
PHP
Python
Python Tutorial
Python Open Source
SQL Server / T-SQL
SQL Server / T-SQL Tutorial
Oracle PL / SQL
PostgreSQL
SQL / MySQL
MySQL Tutorial
VB.Net
VB.Net Tutorial
Flash / Flex / ActionScript
VBA / Excel / Access / Word
XML
XML Tutorial
Microsoft Office PowerPoint 2007 Tutorial
Microsoft Office Excel 2007 Tutorial
Microsoft Office Word 2007 Tutorial
Oracle PL/SQL Tutorial » Trigger » Before Event Trigger 
28. 6. 4. Fire a trigger before an update of the table
SQL>
SQL>
SQL>
SQL> create table myaudit(
  2     id VARCHAR2(BYTE)         NOT NULL,
  3     old_value VARCHAR2(40 BYTE),
  4     new_value VARCHAR2(40 BYTE)
  5  );

Table created.

SQL>
SQL> -- create demo table
SQL> create table Employee(
  2    ID                 VARCHAR2(BYTE)         NOT NULL,
  3    First_Name         VARCHAR2(10 BYTE),
  4    Last_Name          VARCHAR2(10 BYTE),
  5    Start_Date         DATE,
  6    End_Date           DATE,
  7    Salary             Number(8,2),
  8    City               VARCHAR2(10 BYTE),
  9    Description        VARCHAR2(15 BYTE)
 10  )
 11  /

Table created.

SQL>
SQL> -- prepare data
SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2               values ('01','Jason',    'Martin',  to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56'Toronto',  'Programmer')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('02','Alison',   'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78'Vancouver','Tester')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('03','James',    'Smith',   to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78'Vancouver','Tester')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('04','Celia',    'Rice',    to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78'Vancouver','Manager')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('05','Robert',   'Black',   to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78'Vancouver','Tester')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('06','Linda',    'Green',   to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York',  'Tester')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('07','David',    'Larry',   to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York',  'Manager')
  3  /

row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('08','James',    'Cat',     to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
  3  /

row created.

SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select from Employee
  2  /

ID   FIRST_NAME LAST_NAME  START_DAT END_DATE      SALARY CITY       DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01   Jason      Martin     25-JUL-96 25-JUL-06    1234.56 Toronto    Programmer
02   Alison     Mathews    21-MAR-76 21-FEB-86    6661.78 Vancouver  Tester
03   James      Smith      12-DEC-78 15-MAR-90    6544.78 Vancouver  Tester
04   Celia      Rice       24-OCT-82 21-APR-99    2344.78 Vancouver  Manager
05   Robert     Black      15-JAN-84 08-AUG-98    2334.78 Vancouver  Tester
06   Linda      Green      30-JUL-87 04-JAN-96    4322.78 New York   Tester
07   David      Larry      31-DEC-90 12-FEB-98    7897.78 New York   Manager
08   James      Cat        17-SEP-96 15-APR-02    1232.78 Vancouver  Tester

rows selected.

SQL>
SQL>
SQL>
SQL> CREATE OR REPLACE TRIGGER before_employee_salary_update
  2  BEFORE UPDATE OF salary
  3  ON employee
  4  FOR EACH ROW WHEN (new.salary < old.salary * 0.75)
  5  BEGIN
  6    dbms_output.put_line('id ' || :old.id);
  7    dbms_output.put_line('Old salary = ' || :old.salary);
  8    dbms_output.put_line('New salary = ' || :new.salary);
  9    dbms_output.put_line('The salary reduction is more than 25%');
 10
 11  INSERT INTO Myaudit (
 12    id, old_value, new_value
 13  VALUES (
 14    :old.id, :old.salary, :new.salary
 15  );
 16  END before_employee_salary_update;
 17  /

Trigger created.

SQL>
SQL> update employee set salary = 0;

rows updated.

SQL>
SQL>
SQL> select from employee;

ID   FIRST_NAME LAST_NAME  START_DAT END_DATE      SALARY CITY       DESCRIPTION
---- ---------- ---------- --------- --------- ---------- ---------- ---------------
01   Jason      Martin     25-JUL-96 25-JUL-06          0 Toronto    Programmer
02   Alison     Mathews    21-MAR-76 21-FEB-86          0 Vancouver  Tester
03   James      Smith      12-DEC-78 15-MAR-90          0 Vancouver  Tester
04   Celia      Rice       24-OCT-82 21-APR-99          0 Vancouver  Manager
05   Robert     Black      15-JAN-84 08-AUG-98          0 Vancouver  Tester
06   Linda      Green      30-JUL-87 04-JAN-96          0 New York   Tester
07   David      Larry      31-DEC-90 12-FEB-98          0 New York   Manager
08   James      Cat        17-SEP-96 15-APR-02          0 Vancouver  Tester

rows selected.

SQL>
SQL> select from myaudit;

ID   OLD_VALUE                                NEW_VALUE
---- ---------------------------------------- ----------------------------------------
01   1234.56                                  0
02   6661.78                                  0
03   6544.78                                  0
04   2344.78                                  0
05   2334.78                                  0
06   4322.78                                  0
07   7897.78                                  0
08   1232.78                                  0

rows selected.

SQL>
SQL> -- clean the table
SQL> drop table Employee
  2  /

Table dropped.

SQL>
SQL> drop table myaudit;

Table dropped.

SQL>
SQL>
SQL>
28. 6. Before Event Trigger
28. 6. 1. BEFORE EVENT triggers, are for preventing the event from actually happening
28. 6. 2. Insert before trigger
28. 6. 3. Check and change new value in a before-insert trigger
28. 6. 4. Fire a trigger before an update of the table
28. 6. 5. Change data in a before insert or update trigger
28. 6. 6. BEFORE INSERT OR UPDATE OF id
28. 6. 7. Check new value in before insert trigger
28. 6. 8. Check new value in before trigger
28. 6. 9. convert character values to upper case
28. 6. 10. Use trigger to create autoincrement column
28. 6. 11. Implementing Autonumbering Functionality
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.