Hello all,

I recently graduated and started work at a company. I was just assigned with an incredibly important task that I need advice with. I just arrived in this Java project were anyone who knew anything left the company. This project uses an SQL server DB.
We are launching a newer version of this software soon and there are changes to be made to the DB table structure of the old version if someone wants to use the new version of the app. My manager wants me to write a migration script that will modify/alter the table structure of the DB without compromising the data. This tool will be deployed on customer sites, yikes.
I would like to know if the pros of SQL can give me advice on how to proceed. Can I simply compare the table structure of the old tables with the new ones and write alter queries? Or is there a smarter way to do this? Perhaps a tool?
And what should I watch out for?

Thanks
Newbie2sql