c# - how Synchronize database with Context object -

i take new context object in main window context object die when close window

     public main_window()     {         initializecomponent();      }     datacontext db = new datacontext(); 

my problem after created datacontextdb if change date in database management studio not changing in datacontextdb update datacontextdb must close window , open again

example 1 -create object

public partial class  main_window: window  {    public main_window()     {         initializecomponent();      }     datacontext db = new datacontext();  } 

2- select using linq

var q=from in db.employee select new {a.name}; 

result a.name "aaaa"

3-change employee name management studio "bbbb"

4- select using linq again

var q=from in db.employee select new {a.name}; 

result a.name stile "aaaa" why when changed employee name management studio "bbbb" not changed in object datacontext until close window , open again , have other question when create context object load database in object?