There is nothing exactly  like negative test case.
If we test with negative data, then it is called negative 
testing. So no need to add new column for this.
For ex : There is a text box. According to the validation 
it will take only alphanumeric value according to the SRS 
(like 12gh, amit, amit 1234, 11amit). In this case enter 
some special characters in that field ($&)@!) to know 
whether it is accepting that or not. It is called negative 
testing.

Hi Amit!!Thanks for replying. Even i know about -ve Testing.
But, i thought testers can prepare seperate Test Cases for
Negative Testing also.

Negative testing is something which relates to testing the
System against its requirements.
Every System has its requirements & defintions.Test Cases
are written based on the System requirements. If I
understood your question properly , you are confused
regarding where to write the negative test cases? THis is
good question, generally we tend up writing Test Cases as
per System Requirements and we have the results for the
same. Most of Test Engineers however also test -Ve test
cases during the whole testing process , but never record
them in test-procedure. Yes we should record them seprately,
may be by adding few more test cases as mentioning them as
-ve test cases or as suggestions to system requirements. I
hope this answers your question.