Time datatype defaluts to 00:00:00 when no value is there

hi All,
    I have a table with Time(0) as datatype and which is storing 00:00:00 as value when no value is assigned to that filed at the time of the field
so when am retrieving it , I get the value as 00:00:00 so please suggest how to get empty value or replace this value t with empty when getting data from table.