Oracle PL/SQL - Vor dem UPDATE-Trigger-Beispiel

--Creating job_openings table.

CREATE TABLE job_openings
(
    APPLICATION_ID number(10) primary key,
    FIRST_NAME varchar2(50),
    LAST_NAME varchar2(50),
    JOB_EXPERIENCE number(2),
    LAST_APPLIED_DATE date
);

-- Creating TRIGGER

CREATE OR REPLACE TRIGGER trg_before_emp_update
BEFORE UPDATE OF JOB_EXPERIENCE,LAST_APPLIED_DATE
  on job_openings
  FOR EACH ROW

DECLARE

years_since_last_applied number(5);

BEGIN
years_since_last_applied := -1;

  IF(:NEW.LAST_APPLIED_DATE IS NOT NULL) THEN

    SELECT MONTHS_BETWEEN(TO_DATE(sysdate,'DD-MON-YYYY'), TO_DATE(:NEW.LAST_APPLIED_DATE,'DD-MON-YYYY'))/12
      INTO years_since_last_applied FROM dual;

   -- Check whether years_since_last_applied is greater than 2 years or not
    IF (years_since_last_applied <= 2) THEN
      RAISE_APPLICATION_ERROR(-20000,'Previous application attempt must not be done in last 2 years.');
    END IF;
  END IF;

    -- Job experience must be more than or equal to 3 years.
    IF(:new.JOB_EXPERIENCE < 3) THEN
      RAISE_APPLICATION_ERROR(-20000,'Job experience must be more than or equal to 3 years.');
    END IF;

END;

-- setting date format to to 'DD-MON-YYYY'

alter session set nls_date_format = 'DD-MON-YYYY';

INSERT INTO job_openings VALUES (1,'Mark','Sharma',10,'01-JAN-2012');

INSERT INTO job_openings VALUES (2,'Praveen','Kumar',4,'01-DEC-2010');

INSERT INTO job_openings VALUES (3,'Rahul','Kohli',6,null);

-- output
1 rows inserted.
1 rows inserted.
1 rows inserted.

select * from job_openings;

-- Try to update job_experience less than 3 years
UPDATE job_openings SET JOB_EXPERIENCE = 2 where APPLICATION_ID = 1;

-- error
Error report -
ORA-20000: Job experience must be more than or equal to 3 years.
ORA-06512: at "SYSTEM.TRG_BEFORE_EMP_UPDATE", line 21
ORA-04088: error during execution of trigger 'SYSTEM.TRG_BEFORE_EMP_UPDATE'

-- Try to update last_Applied_Date which is less than 2 years
UPDATE job_openings SET LAST_APPLIED_DATE = '10-JUN-2016' where APPLICATION_ID = 3;

-- error
Error report -
ORA-20000: Previous application attempt must not be done in last 2 years.
ORA-06512: at "SYSTEM.TRG_BEFORE_EMP_UPDATE", line 15
ORA-04088: error during execution of trigger 'SYSTEM.TRG_BEFORE_EMP_UPDATE'

--Creating person_records table.

CREATE TABLE person_records
(
    PERSON_ID number(10) primary key,
    FIRST_NAME varchar2(50),
    LAST_NAME varchar2(50),
    HIRE_DATE date,
    UPDATED_BY varchar2(20),
    UPDATED_DATE date
);

CREATE OR REPLACE TRIGGER trg_before_person_update
BEFORE UPDATE
  on person_records
  FOR EACH ROW

DECLARE
username varchar2(20);

BEGIN

  SELECT USER INTO username FROM dual;

  -- Setting updated_by and updated_Date values.
  :NEW.UPDATED_BY := username;
  :NEW.UPDATED_DATE := sysdate;

END;

-- setting date format to to 'DD-MON-YYYY'
alter session set nls_date_format = 'DD-MON-YYYY';

INSERT INTO person_records VALUES (101,'Devil','Khedut',sysdate,null,null);
INSERT INTO person_records VALUES (102,'Kanji','Yadav',sysdate,null,null);

-- output
1 rows inserted.
1 rows inserted.

select * from person_records;

UPDATE person_records SET first_name = 'Lavji' WHERE person_id = 101;

UPDATE person_records SET first_name = 'Jogi' WHERE person_id = 102;

-- output
1 rows updated.
1 rows updated.

select * from person_records;

--Creating bank_transactions table.

CREATE TABLE bank_transactions
(
    TXN_ID number(10) primary key,
    TXN_NUMBER varchar2(20),
    PARTY_NAME varchar2(50),
    TXN_DATE date,
    CREATED_BY varchar2(20),
    CREATED_DATE date
);

--Creating bank_transactions_audit table.

CREATE TABLE bank_transactions_audit
(
    TXN_ID number(10),
    TXN_NUMBER varchar2(20),
    PARTY_NAME varchar2(50),
    TXN_DATE date,
    CREATED_BY varchar2(20),
    CREATED_DATE date
);

--Creating Trigger

CREATE OR REPLACE TRIGGER trg_before_update_txn_audit
BEFORE UPDATE
  ON bank_transactions
  FOR EACH ROW

BEGIN

  -- Insert OLD values in audit table for logging purpose
  INSERT INTO bank_transactions_audit VALUES(:OLD.TXN_ID,:OLD.TXN_NUMBER,
    :OLD.PARTY_NAME,:OLD.TXN_DATE,:OLD.CREATED_BY,:OLD.CREATED_DATE);

END;

--Inserting values

INSERT INTO BANK_TRANSACTIONS values ('1','TXN1234','Peter Thomas','12-MAY-2017','HR',sysdate);

INSERT INTO BANK_TRANSACTIONS values ('2','TXN9999','Jemes Patel','10-JUN-2016','HR',sysdate);

select * from BANK_TRANSACTIONS;

select * from BANK_TRANSACTIONS_AUDIT;

-- output
no rows selected.

--updating values.

UPDATE bank_transactions SET txn_number = 'NEWTXN8080' WHERE txn_id = 1;

UPDATE bank_transactions SET txn_number = 'NEWTXN9595' WHERE txn_id = 2;

-- output
1 rows updated.
1 rows updated.

select * from BANK_TRANSACTIONS;

select * from BANK_TRANSACTIONS_AUDIT;