Oracle之Trigger学习
Trigger学习总结
Note: The size of the trigger cannot be more than32K.
create table emp_trigger
as
select * from emp
CREATE OR REPLACE TRIGGERPrint_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON emp_trigger
FOR EACH ROW
WHEN (new.EMPNO > 5000)
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;
insert intoemp_trigger(empno,sal) values(6000,20);
Oldsalary: New salary: 20 Difference
ONLY the after for each row can look at a"stable" value in the :new record. So, if you doing data validation (eg: this column must be between 1 and30 when this condition is true), you should do that in an AFTER trigger becausethe BEFORE triggers may change the value on you (and since BEFORE triggers firein SOME RANDOM order -- you cannot be assured that your BEFORE trigger firesbefore or after some other BEFORE trigger)
So, use BEFORE FOR EACH row when you needto WRITE to the :new record use AFTER FOR EACH row triggers when you want toVALIDATE the final values in the :new record
In general, you use BEFORE or AFTER triggers to achieve the following results:
■ Use BEFORE row triggers tomodify the row before the row data is written to disk.
■ Use AFTER row triggers toobtain, and perform operations, using the row ID.
INSTEAD OF
INSTEAD OF triggers can bedefined only on views, not on tables.
drop table tr_emp purge;
create table tr_emp
(
empno number(4) primary key,
ename varchar2(50),
deptno number(10)
)
drop table tr_dept purge;
create table tr_dept
(
deptno number(4) primary key,
dname varchar2(50)
);
insert into tr_emp
selectempno,ename,deptno from emp;
insert into tr_dept
selectdeptno,dname from dept;
select * from tr_emp
CREATE OR REPLACE VIEW v_emp_dept AS
SELECTe.empno,e.ename, d.dname, d.deptno
FROM tr_empe, tr_dept d
WHERE e.deptno= d.deptno
Select * from tr_emp select * from tr_dept
| EMPNO |
ENAME |
DEPTNO |
| 5555 |
ggg |
10 |
| 7369 |
SMITH |
20 |
| 7499 |
ALLEN |
30 |
| 7521 |
WARD |
30 |
| 7566 |
JONES |
20 |
| 7654 |
MA & RTIN |
30 |
| 7698 |
BLAKE |
30 |
| 7782 |
CLARK |
10 |
| 7788 |
SCOTT |
20 |
| 7839 |
KING |
10 |
| 7844 |
TURNER |
30 |
| 7900 |
JAMES |
30 |
| 7902 |
FORD |
20 |
| 7934 |
MILLER |
10 |
| 7876 |
ADAMS |
20 |
| DEPTNO |
DNAME |
| 55 |
55 |
| 10 |
ACCOUNTING |
| 20 |
RESEARCH |
| 30 |
SALES |
| 40 |
OPERATIONS |
CREATE OR REPLACE TRIGGER v_emp_dept_insert
INSTEAD OF INSERT ON v_emp_dept
REFERENCING NEW AS n --新数据行用n别名
FOR EACH ROW
DECLARE
rowcnt number;
BEGIN
SELECT COUNT(*) INTO rowcnt FROM tr_emp WHERE empno = :n.empno;
IF rowcnt = 0 THEN --表示是新的雇员
INSERT INTO tr_emp (empno, ename,deptno) VALUES (:n.empno,:n.ename, :n.deptno);--增加新的雇员信息
ELSE --否则是老雇员，则更新雇员的姓名即可
UPDATE tr_emp
SET tr_emp.ename = :n.ename,
tr_emp.deptno = :n.deptno
WHERE tr_emp.empno = :n.empno; --更新
END IF;
SELECT COUNT(*) INTO rowcnt FROM tr_dept WHERE deptno = :n.deptno;
IF rowcnt = 0 THEN --表示是新的部门
INSERT INTO tr_dept (deptno, dname) VALUES (:n.deptno,:n.dname);
ELSE
UPDATE tr_dept
SET tr_dept.dname = :n.dname
WHERE tr_dept.deptno = :n.deptno;
END IF;
END;
FOR EACH ROW Option
CREATE TABLE tr_Emp_log (
Emp_id NUMBER,
Log_date DATE,
New_salary NUMBER(16,2),
Action VARCHAR2(20)
);
create table tr_emp2
(
empno number(4),
ename varchar2(50),
sal number(16,2),
deptno number(2)
)
insert into tr_emp2
selectempno,ename,sal,deptno
from emp
CREATE OR REPLACE TRIGGER Log_salary_increase
AFTER UPDATE ON tr_emp2
FOR EACH ROW
WHEN (new.Sal> 1000)
BEGIN
INSERT INTO tr_Emp_log(Emp_id,Log_date, New_salary, Action)
VALUES(:new.Empno, SYSDATE, :new.SAL, 'NEW SAL');
END;
UPDATE tr_emp2 SET Sal = Sal + 1000.0
WHERE Deptno =20;
select * from tr_Emp_log
This trigger is fired 5 times.
drop TRIGGERLog_salary_increase;
CREATE OR REPLACE TRIGGER Log_emp_update
AFTER UPDATE ON tr_emp2
BEGIN
INSERT INTO tr_Emp_log(Log_date, Action)
VALUES (SYSDATE, 'emp sal changed');
END;
UPDATE tr_emp2 SET Sal = Sal + 1000.0
WHERE Deptno =20;
select * from tr_Emp_log
drop TRIGGER Log_emp_update;
| EMP_ID |
LOG_DATE |
NEW_SALARY |
ACTION |
| 7369 |
2008-08-28 16:36:23 |
1800.00 |
NEW SAL |
| 7566 |
2008-08-28 16:36:23 |
3975.00 |
NEW SAL |
| 7788 |
2008-08-28 16:36:23 |
4000.00 |
NEW SAL |
| 7902 |
2008-08-28 16:36:23 |
4000.00 |
NEW SAL |
| 7876 |
2008-08-28 16:36:23 |
2100.00 |
NEW SAL |
| 2008-08-28 16:41:33 |
emp sal changed |
WHEN
Droptable emp_trigger purge;
create table emp_trigger
as
select * from emp
CREATE OR REPLACE TRIGGERPrint_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON emp_trigger
FOR EACH ROW
WHEN (new.EMPNO*10 > 50000)
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;
insert intoemp_trigger(empno,sal) values(6000,20);
Old salary: New salary: 20 Difference
CREATE OR REPLACE TRIGGERPrint_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON emp_trigger
FOR EACH ROW
WHEN (sqrt(new.EMPNO) >70.7)
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;
insert intoemp_trigger(empno,sal) values(6000,20);
Old salary: New salary: 20 Difference
create or replace function func_test(p1 in integer) return integer is
Result integer;
begin
return(p1*10);
end func_test;
CREATE OR REPLACE TRIGGERPrint_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON emp_trigger
FOR EACH ROW
WHEN func_test(new.EMPNO > 50000)
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;
第 4 行出现错误:
ORA-04076: 无效的 NEW 或 OLD 说明
create or replace function func_test(p1 in integer) return integer
deterministic
is
Result integer;
begin
return(p1*10);
endfunc_test;
CREATE OR REPLACE TRIGGERPrint_salary_changes
BEFORE DELETE OR INSERT OR UPDATE ON emp_trigger
FOR EACH ROW
WHEN (func_test(new.EMPNO) >70.7)
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;
依然出现错误
第 4 行出现错误:
ORA-04076: 无效的 NEW 或 OLD 说明
WHEN(new.Parts_on_hand <new.Reorder_point)
复合trigger(compound trigger) (11g new feature)
CREATE TABLE tr_Emp_log (
Emp_id NUMBER,
Log_date DATE,
New_salary NUMBER(16,2),
Action VARCHAR2(20)
);
create table tr_emp2
(
empno number(4),
ename varchar2(50),
sal number(16,2),
deptno number(2)
)
create or replace trigger log_emp_update
for update of sal on tr_emp2
compound trigger
type t_number is table of number(16, 2) index by pls_integer;
type t_integer is table of integer index by pls_integer;
v_sal t_number;
v_empno t_integer;
BEFORE STATEMENT IS
BEGIN
DBMS_OUTPUT.PUT_LINE('begin working');
END BEFORE STATEMENT;
BEFORE EACH ROW IS
BEGIN
v_empno(v_empno.count + 1) := :NEW.empno;
--do not working
-- v_sal(v_sal.count + 1) :=:NEW.sal;
--dbms_output.put_line('hhhhh'||:NEW.sal);
END BEFORE EACH ROW;
AFTER EACH ROW IS
BEGIN
v_sal(v_sal.count + 1) := :NEW.sal;
dbms_output.put_line('hhhhh'||:NEW.sal);
END AFTER EACH ROW;
AFTER STATEMENT IS
BEGIN
forall i in 1 .. v_sal.count
insert into tr_emp_log(emp_id, log_date,new_salary, action)
values(v_empno(i), sysdate, v_sal(i), 'new sal');
END AFTER STATEMENT;
END;
UPDATE tr_emp2 SET Sal = Sal + 1000.0
WHERE Deptno =20;
Select * from tr_emp_log
| EMP_ID |
LOG_DATE |
NEW_SALARY |
ACTION |
| 7369 |
2008-08-28 20:17:07 |
new sal |
|
| 7566 |
2008-08-28 20:17:07 |
new sal |
|
| 7788 |
2008-08-28 20:17:07 |
new sal |
|
| 7902 |
2008-08-28 20:17:07 |
new sal |
|
| 7876 |
2008-08-28 20:17:07 |
new sal |
|
| 7369 |
2008-08-28 20:20:57 |
6800.00 |
new sal |
| 7566 |
2008-08-28 20:20:57 |
8975.00 |
new sal |
| 7788 |
2008-08-28 20:20:57 |
9000.00 |
new sal |
| 7902 |
2008-08-28 20:20:57 |
9000.00 |
new sal |
| 7876 |
2008-08-28 20:20:57 |
7100.00 |
new sal |
Detecting the DML Operation that Fired a Trigger
IF INSERTING THEN... END IF;
IF UPDATING THEN ...END IF;
CREATE OR REPLACETRIGGER ...
... UPDATE OF Sal,Comm ON emp ...
BEGIN
... IF UPDATING('SAL') THEN ... END IF;
END;
Java Trigger
create or replace and compile java source named JT as
importjava.sql.*;
importjava.io.*;
importoracle.sql.*;
importoracle.oracore.*;
public class JavaTriggers
{
public static void beforeDelete(NUMBER old_id, CHAR old_name)
{
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;
}
}
CREATE OR REPLACE PROCEDUREBefore_delete (Id IN NUMBER, Ename VARCHAR2)
IS language Java
name JavaTriggers.beforeDelete (oracle.sql.NUMBER,oracle.sql.CHAR)';
CREATE OR REPLACETRIGGER Pre_del_trigger BEFORE DELETE ON Tab
FOR EACH ROW
CALL Before_delete(:old.Id, :old.Ename)
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