If your application uses a relational database, odds are good that updating the application will require changing the database structure. While tools are available for migrating databases in most frameworks, there is no silver bullet.
Unit testing is a valuable skill to have, no matter where your code runs or what it does. It reduces the error rate of your software and can often help force a better structure into your code. In addition, this practice can make it easier to make large changes to your software with less risk, as well as making it easier for new developers to understand the structure of your software.