Need a Better Regular Expression for Validating Dates

Question

I have data coming from file with date in the format DD-MON-YY.
I have created the following regular expression:
'^([0-2]{1}[0-9]{1}|[3]{1}[0-1]{1})-(JAN|FEB|MAR|A PR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC|Jan|Feb|Mar|Apr |May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)-[[:digit:]]{2}$'
However, it doesn't catch dates like 31-APR, 29-FEB. Can someone make changes to it to make it foolproof
WITH temp AS
(SELECT '29-FEB-07' AS COL1 FROM DUAL
UNION ALL
SELECT '31-APR-08' FROM DUAL
UNION ALL
SELECT '32-JAN-08' FROM DUAL
UNION ALL
SELECT '29-MAR-08' FROM DUAL
UNION ALL
SELECT '31-JAN-08' FROM DUAL)
SELECT COL1,
CASE WHEN REGEXP_LIKE(COL1,'^([0-2]{1}[0-9]{1}|[3]{1}[0-1]{1} )-(JAN|FEB|MAR|APR|MAY|JUN|JUL|AUG|SEP|OCT|NOV|DEC |Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)- [[ :digit:]]{2}$')
THEN 'VALID'
ELSE 'INVALID'
END
FROM TEMP;

Answer 1

Hi,
Please check this function.
The function works for the dates in the format 'DD-MON-YYYY','DD/MON/YYYY'.
create or replace function date_validation_f(v_date varchar2) return varchar2 is
v_ip_date     date;
v_ip_date_ch  varchar2(20);
v_ip_year  number;
v_ip_month char(3);
v_ip_day   number;
v_return   varchar2(10);
v_leap_year_check number :=0 ;
type v_month_name_typ      is varray (12) of char(3);
type v_month_last_day_typ  is varray (12) of number(2);
v_month_name     v_month_name_typ    :=v_month_name_typ('JAN','FEB','MAR','APR','MAY','JUN','JUL','AUG','SEP','OCT','NOV','DEC');
v_month_last_day v_month_last_day_typ:=v_month_last_day_typ(31,28,31,30,31,30,31,31,30,31,30,31);
begin
--Assuming that input date is in the format DD-MON-YYYY or DD/MON/YYYY
v_return := 'invalid';
v_ip_date := to_date(v_date);
v_ip_date_ch := to_char(v_ip_date,'DD-MON-YYYY');
dbms_output.put_line('v_ip_date_ch := '||v_ip_date_ch);
v_ip_month   := substr(v_ip_date_ch,4,3);
dbms_output.put_line('v_ip_month := '||v_ip_month);
v_ip_day    := substr(v_ip_date_ch,1,2);
dbms_output.put_line('v_ip_year := '||v_ip_year);
v_ip_year     := to_number(substr(v_ip_date_ch,8,4));
dbms_output.put_line('v_ip_day := '||v_ip_day);
-- Ckecking for leap year
if MOD(v_ip_year,4)=0 then
  if MOD(v_ip_year,100)=0 then
    if MOD(v_ip_year,400)=0 then
       v_leap_year_check:=1;
    end if;
  else
       v_leap_year_check:=1;
  end if;
end if;
if v_leap_year_check = 1 then
   v_month_last_day(2):=29;
end if;
for i in 1..12
loop
if v_month_name(i)=upper(v_ip_month) then
     if v_ip_day between 1 and v_month_last_day(i) then
        v_return := 'valid';
        exit;
    else
        v_return := 'invalid';
        exit;
    end if;
end if;
end loop;
dbms_output.put_line('v_return := '||v_return );
return v_return;
exception
when others then
return v_return;
dbms_output.put_line(SQLERRM);
end;you can use this function in SELECT statement.
Edited by: Sreekanth Munagala on Nov 13, 2008 11:25 PM