Current date of birth for my column is null getting error....

Question

Hi All..
i am calucating the current date of birth for my column which is date field and accept nulls (cust_dob) in my table.
select cust_dob,Add_Months(
to_date(cust_dob, 'dd/mm/yyyy'),
Months_Between(
trunc(sysdate, 'year'),
trunc(to_date(cust_dob, 'dd/mm/yyyy'), 'yyyy')
) as current_dob from m_customer_hdr
when i execute my query in toad. it is showing the result. but when i scroll down to see data it thow error as
ORA-01858: a non-numeric character was found where a numeric was expected...
Thanks in advance..
Abdul rafi

Answer 1

What datatype is cust_dob datatype. Somehow I have a feeling it is DATE. If so, expression:
to_date(cust_dob, 'dd/mm/yyyy')Implicitly converts cust_dob to a string using session nls_date_format and then converts it back to date using 'dd/mm/yyyy' format. Now if NULL dob are fetched first, you might get something like:
SQL> ALTER SESSION SET NLS_DATE_FORMAT='DD-MON-RR';
Session altered.
SQL> SET SERVEROUTPUT ON
SQL> BEGIN
  2      FOR v_rec IN (SELECT  TO_DATE(cust_dob,'mm/dd/yyyy') cust_dob
  3                      FROM  (
  4                             SELECT TO_DATE(NULL) cust_dob FROM DUAL UNION ALL
  5                             SELECT TO_DATE(NULL) cust_dob FROM DUAL UNION ALL
  6                             SELECT TO_DATE(NULL) cust_dob FROM DUAL UNION ALL
  7                             SELECT sysdate cust_dob FROM DUAL
  8                            )
  9                   ) LOOP
10        DBMS_OUTPUT.PUT_LINE('DOB = "' || v_rec.cust_dob || '"');
11      END LOOP;
12  END;
13  /
DOB = ""
DOB = ""
DOB = ""
BEGIN
ERROR at line 1:
ORA-01858: a non-numeric character was found where a numeric was expected
ORA-06512: at line 2So if column CUST_DOB is DATE, use:
select cust_dob,Add_Months(
cust_dob,
Months_Between(
trunc(sysdate, 'year'),
trunc(cust_dob, 'yyyy')
) as current_dob from m_customer_hdrSY.