Oracle PL/SQL Tutorial/Trigger/Row Level Trigger — различия между версиями

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Версия 13:45, 26 мая 2010

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>