Oracle PL/SQL Tutorial/Trigger/Row Level Trigger
Содержание
A row-level trigger
<source lang="sql">
SQL> SQL> SQL> create table myaudit(
2 id VARCHAR2(4 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(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> 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; 8 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 8 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 8 rows selected. SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL> drop table myaudit; Table dropped. SQL> SQL></source>
Change value in Row level trigger
<source lang="sql">
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></source>
FOR EACH ROW clause identifies this as a row-level trigger
The trigger code contained within the BEGIN and END keywords is to be run once for each row.
<source lang="sql">
SQL> SQL> create table myaudit(
2 id VARCHAR2(4 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(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> 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; 8 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 8 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 8 rows selected. SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL> drop table myaudit; Table dropped. SQL> SQL> SQL></source>
For each row when condition
<source lang="sql">
SQL> SQL> CREATE TABLE golf_scores
2 (timestamp DATE NOT NULL, 3 score NUMBER NOT NULL, 4 commentary VARCHAR2(30));
Table created. SQL> SQL> CREATE OR REPLACE TRIGGER golf_commentary_under_par
2 BEFORE INSERT ON golf_scores 3 FOR EACH ROW 4 WHEN (NEW.score < 72) 5 BEGIN 6 :NEW.rumentary := "Under Par"; 7 END; 8 /
Trigger created. SQL> SQL> SQL> DROP TABLE golf_scores; Table dropped. SQL></source>
