Help with a basic trigger to capture OS_USER

Question

Below is the trigger and it does not work - help very much appreciated
CREATE OR REPLACE TRIGGER trg_master_tab_aft
AFTER INSERT OR UPDATE OR DELETE
ON master_tab
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
DECLARE
BEGIN
     IF INSERTING THEN
     INSERT INTO master_tab_hst values (:NEW.col1,
     :NEW.OSUSER := SELECT SYS_CONTEXT('USERENV', 'OS_USER')  FROM dual
     ,'I'
     ,SYSDATE);
     ELSIF UPDATING THEN
     INSERT INTO master_tab_hst (:NEW.col1,
     :NEW.OSUSER := SELECT SYS_CONTEXT('USERENV', 'OS_USER')  FROM dual
     ,'U'
     ,SYSDATE);
     ELSIF DELETING THEN
     INSERT INTO master_tab_hst (:OLD.col1,
     :NEW.OSUSER := SELECT SYS_CONTEXT('USERENV', 'OS_USER')  FROM dual
     ,'D'
     ,SYSDATE);
     END IF;
EXCEPTION
     WHEN OTHERS THEN
       -- Consider  the error and then re-raise
       RAISE;
END ;

Answer 1

Hello Srini,
Please see if it helps you.
CREATE OR REPLACE TRIGGER trg_master_tab_aft
BEFORE  INSERT OR UPDATE OR DELETE
   ON master_tab    FOR EACH ROW
BEGIN
   IF INSERTING THEN
   INSERT INTO master_tab_hst
   ( STR_NUM,
     TERM_ID,
     HOST_ENV,
     USR_TERMINAL,
     SESSION_USR,
     OS_USER,
     ACTION_DATE,
    ACTION_NAME)
   VALUES
   ( :NEW.STR_NUM,
     :NEW.TERM_ID,
          sys_context('USERENV', 'HOST'),
          sys_context('USERENV', 'TERMINAL'),
          sys_context('USERENV', 'SESSION_USER'),
          sys_context('USERENV', 'OS_USER'),
               SYSDATE,
               'INSERT');
    ELSIF UPDATING THEN
   INSERT INTO master_tab_hst
   ( STR_NUM,
     TERM_ID,
     HOST_ENV,
     USR_TERMINAL,
     SESSION_USR,
     OS_USER,
     ACTION_DATE,
    ACTION_NAME)
   VALUES
   ( TRUNC(:OLD.STR_NUM)||','||:NEW.STR_NUM,
     TRUNC(:OLD.TERM_ID)||','||:NEW.TERM_ID,
          sys_context('USERENV', 'HOST'),
          sys_context('USERENV', 'TERMINAL'),
          sys_context('USERENV', 'SESSION_USER'),
          sys_context('USERENV', 'OS_USER'),
               SYSDATE,
               'UPDATE');          
    ELSIF DELETING THEN
   INSERT INTO master_tab_hst
   ( STR_NUM,
     TERM_ID,
     HOST_ENV,
     USR_TERMINAL,
     SESSION_USR,
     OS_USER,
     ACTION_DATE,
    ACTION_NAME)
   VALUES
   ( :OLD.STR_NUM,
     :OLD.TERM_ID,
          sys_context('USERENV', 'HOST'),
          sys_context('USERENV', 'TERMINAL'),
          sys_context('USERENV', 'SESSION_USER'),
          sys_context('USERENV', 'OS_USER'),
               SYSDATE,
               'DELETE');
    END IF; 
EXCEPTION
     WHEN OTHERS THEN
       -- Consider  the error and then re-raise
       RAISE;
END;