Parameswaran, If you just want to import the columns in a different order, you can often configure your database's import facility to do so.
For something more complicated, you can write a script in any language that accesses the database. I'll assume you know Java since you are asking here. In Java, you would loop through the Excel spreadsheet and use a PreparedStatement to update the database. You'd probably want to use a batch update so it goes faster.