Oracle PL/SQL/Trigger/After Update Trigger
Create an after update trigger
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> -- 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> --after update trigger
SQL> CREATE OR REPLACE TRIGGER employee_after_update
2 AFTER UPDATE
3 ON employee
4 FOR EACH ROW
5
6 DECLARE
7 v_username varchar2(10);
8
9 BEGIN
10
11 -- Find username of person performing UPDATE into table
12 SELECT user INTO v_username
13 FROM dual;
14
15 dbms_output.put_line("By: "||v_username);
16 dbms_output.put_line(":new.id: "||:new.id);
17 dbms_output.put_line(":new.first_name: "||:new.first_name);
18 dbms_output.put_line(":new.last_name: "||:new.last_name);
19 dbms_output.put_line(":old.id: "||:old.id);
20 dbms_output.put_line(":old.first_name: "||:old.first_name);
21 dbms_output.put_line(":old.last_name: "||:old.last_name);
22
23 END;
24 /
Trigger created.
SQL>
SQL> update employee set first_name = "new";
By: sqle
:new.id: 01
:new.first_name: new
:new.last_name: Martin
:old.id: 01
:old.first_name: Jason
:old.last_name: Martin
By: sqle
:new.id: 02
:new.first_name: new
:new.last_name: Mathews
:old.id: 02
:old.first_name: Alison
:old.last_name: Mathews
By: sqle
:new.id: 03
:new.first_name: new
:new.last_name: Smith
:old.id: 03
:old.first_name: James
:old.last_name: Smith
By: sqle
:new.id: 04
:new.first_name: new
:new.last_name: Rice
:old.id: 04
:old.first_name: Celia
:old.last_name: Rice
By: sqle
:new.id: 05
:new.first_name: new
:new.last_name: Black
:old.id: 05
:old.first_name: Robert
:old.last_name: Black
By: sqle
:new.id: 06
:new.first_name: new
:new.last_name: Green
:old.id: 06
:old.first_name: Linda
:old.last_name: Green
By: sqle
:new.id: 07
:new.first_name: new
:new.last_name: Larry
:old.id: 07
:old.first_name: David
:old.last_name: Larry
By: sqle
:new.id: 08
:new.first_name: new
:new.last_name: Cat
:old.id: 08
:old.first_name: James
:old.last_name: Cat
8 rows updated.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>
SQL>
Simple AFTER update trigger
SQL> create table t( x int,
2 constraint t_pk primary key(x)
3 );
Table created.
SQL>
SQL>
SQL> create trigger t_trigger AFTER update on T for each row
2 begin
3 dbms_output.put_line( "Updated x=" || :old.x || " to x=" || :new.x );
4 end;
5 /
Trigger created.
SQL>
SQL> insert into t values ( 1 );
1 row created.
SQL> insert into t values ( 2 );
1 row created.
SQL>
SQL> set serveroutput on
SQL>
SQL> update t set x = 2;
Updated x=1 to x=2
Updated x=2 to x=2
update t set x = 2
*
ERROR at line 1:
ORA-00001: unique constraint (sqle.T_PK) violated
SQL>
SQL> update t set x = x+1;
Updated x=1 to x=2
Updated x=2 to x=3
2 rows updated.
SQL>
SQL>
SQL> drop table t;
Table dropped.
SQL>
SQL>
SQL>