title: How to upgrade database schema built with an ORM tool?
body: <p>I'm looking for a general solution for upgrading database schema with ORM tools, like JPOX or Hibernate. How do you do it in your projects?</p>
  
  <p>The first solution that comes to my mind is to create my own mechanism for upgrading databases, with SQL scripts doing all the work. But in this case I'll have to remember about creating new scripts every time the object mappings are updated. And I'll still have to deal with low-level SQL queries, instead of just defining mappings and allowing the ORM tools to do all the job...</p>
  
  <p>So the question is how to do it properly. Maybe some tools allow for simplifying this task (for example, I heard that Rails have such mechanism built-in), if so please help me decide which ORM tool to choose for my next Java project.</p>