Question

My team is developing a large java application which extensively queries a MySQL database (in different classes and modules). I’d like to known if there is a pattern that allows me to be notified at compile time if there are queries that refer to a wrong table structure (for instance if I remove or add a field on a table and the query string refers to it), in order to prevent runtime errors. This should work also for JOIN queries.

Answer 1

There’s an open-source tool called DODS (Data Object Design Studio) that could do what you want. The DODS tool was originally part of the Enhydra Java application server project, and since the company backing that project went kablooey in 2002, DODS has been hosted and maintained at ObjectWeb. Anyway, it’s open-source (LGPL).

http://forge.objectweb.org/projects/dods

The concept is that you describe your schema in an XML file, and DODS generates Java POJO classes with which you can query and manipulate the database tables. Of course every time you change your schema, you need to run DODS again to re-generate the ORM classes, and recompile your app against them.

But the result is that if a table or column disappears, and your app is querying database metadata that no longer exists, you do get a compile-time error, because your code is now calling a corresponding class or method that no longer exists.