UPDATE ... RETURNING does not return new value

Question

Hi all,
I've created the following objects in Oracle DB 10.2.0.3.0:
CREATE TABLE TAB1
     ID          NUMBER          PRIMARY KEY,
     EDITED_AT     DATE,
     VALUE          VARCHAR2(64)
CREATE SEQUENCE S_TAB1
     INCREMENT BY 1
     START WITH 1;
CREATE TRIGGER T_TAB1_BIE
BEFORE INSERT OR UPDATE ON TAB1
FOR EACH ROW
BEGIN
     IF INSERTING THEN
          SELECT S_TAB1.NEXTVAL INTO :NEW.ID FROM DUAL;
     END IF;
     :NEW.EDITED_AT := SYSDATE;
END;
/Then I tried to do the following in SQL Plus:
SQL> insert into tab1(value) values('ddd');
1 row created.
SQL> commit;
Commit complete.
SQL>
SQL> select * from tab1;
        ID EDITED_AT           VALUE
         1 27.03.2008 17:01:24 ddd
SQL>
SQL> declare dt date; val varchar2(64);
  2  begin update tab1 set value = 'ddd' where id = 1 returning edited_at, value into dt, val;
  3  dbms_output.put_line('txt = ' || dt || ', ' || val);
  4  end;
  5  /
txt = 27.03.2008 17:01:24, ddd
PL/SQL procedure successfully completed.
SQL>
SQL> select * from tab1;
        ID EDITED_AT           VALUE
         1 27.03.2008 17:02:12 ddd
SQL>As it can be seen Returning clause of an Update statement does not return a new date, i.e. 27.03.2008 17:02:12, that was updated by the trigger, it returns an old one - 27.03.2008 17:01:24. Please advise me why Database returns an old value? I do believe that UPDATE ... RETURNING ... statement should return new, generated by the trigger, value.
Thanks in advance.
Regards,
Yerzhan.

Answer 1

you need to explicitly include the column in your UPDATE statement SET clause that you expect to return the result you want it to be. here's what i think what happened even though you have a trigger the first statement that was processed was your update statement. at the time of the update it has to return the current values to the returning clause that is the values on the table. now comes next the trigger which gives edited_at column a new value. when the trigger got fired the process don't return anymore to the UPDATE RETURNING statement. it's like each sequence of codes does not executes in parallel.
  SQL> CREATE TABLE TAB_1
    2  (
    3   ID  NUMBER  PRIMARY KEY,
    4   EDITED_AT DATE,
    5   VALUE  VARCHAR2(64)
    6  );
  Table created.
  SQL> CREATE SEQUENCE S_TAB1
    2   INCREMENT BY 1
    3   START WITH 1;
  Sequence created.
  SQL> CREATE TRIGGER T_TAB1_BIE
    2  BEFORE INSERT OR UPDATE ON TAB_1
    3  FOR EACH ROW
    4  BEGIN
    5   IF INSERTING THEN
    6    SELECT S_TAB1.NEXTVAL INTO :NEW.ID FROM DUAL;
    7   END IF;
    8   :NEW.EDITED_AT := SYSDATE;
    9  END;
   10  /
  Trigger created.
  SQL> insert into tab_1(value) values('ddd');
  1 row created.
  SQL> commit;
  SQL> select * from tab_1;
          ID EDITED_AT            VALUE
           1 28-mar-2008 10:31:18 ddd
  SQL> declare dt date; val varchar2(64);
    2  begin update tab_1 set value = 'ddd', edited_at = sysdate
    3        where id = 1 returning edited_at, value into dt, val;
    4  dbms_output.put_line('txt = ' || dt || ', ' || val);
    5  end;
    6  /
  txt = 28-mar-2008 10:32:39, ddd
  PL/SQL procedure successfully completed.
  SQL> select * from tab_1;
          ID EDITED_AT            VALUE
           1 28-mar-2008 10:32:39 ddd
  SQL>