Oracle PL/SQL Tutorial/Trigger/Row Level Trigger
Содержание
A row-level trigger
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>
Change value in Row level trigger
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>
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.
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>
For each row when condition
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>