create or replace PACKAGE dt 
IS
   /* The replacement for TO_DATE */
   FUNCTION val (value_in IN VARCHAR2) RETURN DATE;

/* Note: In Oracle8i and above, you can now supply a list of
date formats in the NLS_DATE_FORMAT parameter and it will try
to use all of those. */

END dt;
/
create or replace PACKAGE BODY dt 
IS
   /* 
   || Declare the structure of the PL/SQL table which will hold
   || the masks. Then declare the table itself.
   */
   TYPE mask_tabtype IS TABLE OF VARCHAR2 (30) INDEX BY BINARY_INTEGER;
   fmts mask_tabtype;

   fmt_count INTEGER;

   FUNCTION val (value_in IN VARCHAR2) RETURN DATE
   IS
      retval DATE := NULL;

      /* Loop index for the scan through the masks */
      mask_index INTEGER := 1;

      /* Boolean to terminate loop if date was converted */
      date_converted BOOLEAN := FALSE;
   BEGIN
      /* Convert from masks in table */
      IF value_in IS NULL
      THEN
         date_converted := TRUE;
      ELSE
         /* 09/000 TVP - Improve performance by testing with default */
         BEGIN
            /* Try to convert string using mask in table row */
            retval := TO_DATE (value_in);
            date_converted := TRUE;
         EXCEPTION 
            WHEN OTHERS 
            THEN 
               date_converted := FALSE;
         END;
         
         /* Loop through the rows in the table... */
         WHILE mask_index <= fmt_count AND NOT date_converted
         LOOP
            BEGIN
               /* Try to convert string using mask in table row */
               retval := TO_DATE (value_in, fmts (mask_index));
               p.l ('Converting with ' || fmts (mask_index));
               date_converted := TRUE;
            EXCEPTION 
               WHEN OTHERS 
               THEN 
                  retval := NULL;
                  mask_index:= mask_index+ 1;
            END;
         END LOOP;
      END IF;

      IF date_converted
      THEN
         RETURN retval;
      ELSE
         RAISE VALUE_ERROR;
      END IF;
   END val;
   
BEGIN
   /* ------------ Initialization Section of Package ------------*/
   fmts(1) := 'DD-MON-RR';
   fmts(2) := 'DD-MON-YYYY';
   fmts(3) := 'DD-MON';
   fmts(4) := 'MM/DD';
   fmts(5) := 'MM/RR';
   fmts(6) := 'MMDDRR';
   fmts(7) := 'MM/YYYY';
   fmts(8) := 'MM/DD/RR';
   fmts(9) := 'MM/DD/YYYY';
   fmts(10) := 'MMDDYYYY';
   fmts(11) := 'YYYYMMDD';
   fmts(12) := 'RRMMDD';
   fmt_count := 12;
      
END dt;
/


/*======================================================================
| Supplement to the third edition of Oracle PL/SQL Programming by Steven
| Feuerstein with Bill Pribyl, Copyright (c) 1997-2002 O'Reilly &
| Associates, Inc. To submit corrections or find more code samples visit
| http://www.oreilly.com/catalog/oraclep3/
*/