Hi Veera,
Thanks for the reply. Actually I have tried that method only but the customers are not sure about the threshold time.
I have checked whether name, date, hour and minute matches with system variables but still if it is entered at 11:59:59 pm, all the values including the date changes. 
So, Is there any other better way to find it? like is there any table that creates a record every time comment is entered ?
Regards,
Parthi