Hi Enya,
You can use a huige number of display transformation for times:
Please Read:
http://www.dba-oracle.com/t_nls_date_format_sysdate.htm***************************************
>> (MTTD)>=TO_DATE('000000','HH24:MI:SS').
CODE
IF TO_DATE(MTTD)>=TO_DATE('23:11:01','HH24:MI:SS').
You are defining MTTD as a DATE datatype.
You would need a to_char to see the contents of MTTD!
Instead of converting the string to a date, do it the other way around!