TO_DATE misbehaving in PL/SQL function

Question

Hello,
Probably just missing something obvious, but does anyone have any ideas why the TO_DATE below doesn't work?
create or replace function columnsforest(target_table_name in varchar2)
  return varchar2
as columns_string varchar2(32000);
cursor getColumnNames (target_table_name varchar2) is
  select column_name, data_type from user_tab_cols
  where table_name = target_table_name;
begin
  for col in getColumnNames(target_table_name)
  loop
    if (col.column_name != 'STUDY_ID')
    then
      if col.data_type = 'DATE'
      then columns_string := columns_string || 'TO_DATE('||col.column_name||',''YYYY-MM-DD HH24:MI:SS'') as D'||col.column_name||', ';
      else columns_string := columns_string || col.column_name || ', ';
      end if;
    end if;
  end loop;
  columns_string := rtrim(columns_string,', ');
return columns_string;
end;Say col.column_name (a string) was DATE_CHANGED, I would expect the line of code above to produce the following:
TO_DATE(DATE_CHANGED,'YYYY-MM-DD HH24:MI:SS') as DDATE_CHANGEDBut I always end up with my default date presentation (06-JUN-06). What am I doing wrong? I know this line is being executed because the D always appears before the column name...
Thanks for your help,
Gary

Answer 1

Hello
It's down to your NLS_DATE_FORMAT:
SQL> select sysdate from dual;
06-JUN-06
SQL> select to_date('2006-06-06','YYYY-MM-DD') from dual;
06-JUN-06
SQL> select to_date('2006-06-06 14:43:00','YYYY-MM-DD hh24:mi:ss') from dual;
06-JUN-06
SQL> alter session set nls_date_format='DD-MON-YYYY HH24:MI:SS'
  2  /
Session altered.
SQL> select to_date('2006-06-06 14:43:00','YYYY-MM-DD hh24:mi:ss') from dual;
06-JUN-2006 14:43:00
SQL> alter session set nls_date_format='YYYY-MM-DD HH24:MI:SS'
  2  /
Session altered.
SQL> select to_date('2006-06-06 14:43:00','YYYY-MM-DD hh24:mi:ss') from dual;
2006-06-06 14:43:00
SQL> select sysdate from dual;
2006-06-06 14:44:37HTH
David