All that you need to enable LINQ in your project is to add reference to Db4objects.Db4o.Linq.dll and use it in your class:
Let's start from looking at some simple examples. First of all - fill up the database with some objects:
And use LINQ syntax to select Pilots by name and points:
We use our db4o database as a datasource, the rest of the syntax is typical for LINQ queries. Using Object-Oriented language for creating queries gives us an advantage of creating very flexible select criteria and provides a benefit of compile-checked code.