Hi Malatesh, good question. Many people tend to take it lightly.
The choice of data store completely depends upon the type of desktop application you are creating.
1. If you want a light weight and portable option, I'll recommend SQLite. For instance browsers like Mozilla Firefox use SQLite to store the bookmarks we create. But it has certain limitations. Visit http://www.sqlite.org/ for more details.
2. Another powerful option, I recently learned about is Cassandra. I believe you must be using Facebook and I hope you agree that it is fairly quick. It uses Cassandra as its backend. I think this is a very good option, since you get to learn something new too. http://cassandra.apache.org/
3. Other options include Oracle, MSSQL, MYSQL and PostgreSQL and are more powerful, conventional databases that allow loads of capabilities.
Thank you Pranav Raulkar and Nico Van Belle, that looks like exactly what I was looking for. Let me go through all the hints you have given. By the way I am having the data exactly like bank transaction details.