We continue on our path to make a web application using C# and .NET. After choosing the front-end technology in part 1 , picking the backend server tech in part 2 , and deploying to Azure in part 3 , we’re going to concentrate on choosing the database. With emphasis on .NET and Azure technologies of course. A database, or rather databases, is one of the most important aspects of any big application.

In this article, you'll see how frameworks like Entity Framework and MongoDB C# driver use expressions trees to make that conversion. And you'll see how to use expression trees yourself to build dynamic queries. Those are queries that you aren't able to create at compile time because you'll know how the query should look like only at runtime.