Question

I need to develop a trigger in PL/SQL (Oracle) before INSERT.

In this table there is a column (cdat) of type DATE.

Let’s say i do INSERT INTO myTbl (123,'12/05/2011');

In my trigger the :NEW.CDAT is converted in the final date system or it’s still a varchar?

Do I need to do a TO_DATE(:NEW.CDAT) to get the date value?

Answer 1

:NEW.CDAT will be a date. The :new and :old variables in triggers are always the type of the destination field.

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I wasn’t able to find anything in the Oracle documentation that confirms my statement, but I was able to devise some experimental proof:

CREATE TABLE test2 (a DATE);

CREATE OR REPLACE TRIGGER bu_test2
   BEFORE INSERT OR UPDATE
   ON test2
   FOR EACH ROW
DECLARE
   PROCEDURE type_test(in_type DATE) IS
   BEGIN
      DBMS_OUTPUT.put_line('date');
   END;
   PROCEDURE type_test(in_type VARCHAR2) IS
   BEGIN
      DBMS_OUTPUT.put_line('varchar2');
   END;
BEGIN
   type_test(:new.a);
END;

INSERT INTO test2
  VALUES   ('24-Mar-2011');

Since type_test is overloaded, Oracle will choose which procedure to use based on the type being passed in. The results of this script are:

Table created.
Trigger created.
date
1 row created.