Entity Framework Connections C# with Example

Entity Framework exposes abstraction classes that are used to interact with underlying databases in the form of 
classes like DbContext. These contexts generally consist of DbSet properties that expose the available collections 
that can be queried : 
public class ExampleContext: DbContext 
{ 
public virtual DbSet Widgets { get; set; } 
} 
The DbContext itself will handle making the connections with the databases and will generally read the appropriate 
Connection String data from a configuration to determine how to establish the connections : 
public class ExampleContext: DbContext 
{ 
// The parameter being passed in to the base constructor indicates the name of the 
// connection string 
 

public ExampleContext() : base("ExampleContextEntities") 
{ 
} 
public virtual DbSet Widgets { get; set; } 
} 
Executing Entity Framework Queries 
Actually executing an Entity Framework query can be quite easy and simply requires you to create an instance of 
the context and then use the available properties on it to pull or access your data 
using(var context = new ExampleContext()) 
{ 
// Retrieve all of the Widgets in your database 
var data = context.Widgets.ToList(); 
} 
Entity Framework also provides an extensive change-tracking system that can be used to handle updating entries 
within your database by simply calling the SaveChanges() method to push changes to the database : 
using(var context = new ExampleContext()) 
{ 
// Grab the widget you wish to update 
var widget = context.Widgets.Find(w => w.Id == id); 
// If it exists, update it 
if(widget != null) 
{ 
// Update your widget and save your changes 
widget.Updated = DateTime.UtcNow; 
context.SaveChanges(); 
} 
}