C# client applications can talk to a database using ADO.NET. Collectively, it is a set of classes (often called a framework ) that can help you connect a datasource, such as an XML file or a database. Using these classes (and the corresponding methods), you can manipulate the required data. It is another big topic, but I limit the discussion to how a simple C# application can talk to a RDBMS (relational database management system) using SQL queries.
When I talk about RDBMS, there are multiple choices. For example, Oracle, Microsoft SQL Server, and MySQL are some of the ...
