Ancheswaroop,
I'm going to be a little harsh here. The information you require is in this thread, with great examples from Dan and an idea from myself. Please read back through the replies and look at what has been given to you by the way of examples, and use them.
If you have a table that holds a date that is not in a date format, then substr is the answer. The answer that you require is here, with examples. Yes, Dan or I or many others could give you the answer, but the whole idea behind tek tips is that you ask questions and learn from the replies.
Please have a go with some SQL, and if you are still struggling, get back to us with the SQL you have written, and we will attempt to lead you to an answer.
Sorry to be so negative, but I really do think you have enough information in this thread to give it a go.
Marc