title: ASP.NET Data source controls
body: <p>I am learning ASP.NET. I noticed there are several types of ASP.NET data source controls available in Microsoft Visual studio, including SqlDataSource, AccessDataSource, ObjectDataSource, and XmlDataSource.  Does anyone could explain the differences among SqlDataSource, AccessDataSource, ObjectDataSource, and XmlDataSource?  Which one is more useful in the real world?  Thank you.</p>