Change data in a before insert or update trigger : Before Event Trigger « Trigger « Oracle PL/SQL Tutorial






SQL>
SQL> -- create demo table
SQL> create table Employee(
  2    ID                 VARCHAR2(4 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> CREATE OR REPLACE TRIGGER employee_insert_update
  2    BEFORE INSERT OR UPDATE ON employee
  3    FOR EACH ROW
  4  DECLARE
  5    dup_flag  INTEGER;
  6  BEGIN
  7       --Force all employee names to uppercase.
  8  :NEW.first_name := UPPER(:NEW.first_name);
  9  END;
 10  /

Trigger created.

SQL>
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  /

1 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  /

1 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  /

1 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  /

1 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  /

1 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  /

1 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  /

1 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  /

1 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

8 rows selected.

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

Table dropped.

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