This seems like a homework/interview question (what's with the number "4" in the title?). Anybody looking at it, I would not answer it. And to add to it, I just saw a question very much like this one like a day ago. Either two people are taking the same test, or the same person signed up using a different CP login.
EDITFound it:
http://www.codeproject.com/answers/44338/Implementing-search-functionality-other-than-SQL-q.aspx
Probably just the same person under a different account posting the same questions.