@celko - I respect your experience and expertise. I am not a great programmer and I am not writing any books. I didn't work in ANSI/ISO SQL Standards Committee either. I am just working on an issue. I posted the problem so that people of my knowledge also can understand and benefit from the solutions provided by experts. As long as people understand what my problem is I am fine. You understood what my question was, other people who replied understood what my question was and I believe any person who don't know anything about sql can also understand what my question is. If it makes you feel happy and sleep well tonight, I would be more than happy to say that I DON'T KNOW ANYTHING. If everyone writes like you and use the same language or Netiquette that you use, everyone will be authors, who will be the readers then? I just wanted to be a reader not an author.