How to retrieve data from database in a Silverlight application by coding in a Service File

I have a Silverlight Application,with Code in C# in Visual Studio 2010开发者_运维百科. My requirement is i have a form with many different controls(Example textboxes,combo boxes). I want to fill data in all these controls from Database,the values are comiing from different tables of the database(like CountryName in Combo from CountryMaster,CityName in Combo from CityMaster) etc.Now how can i construct methods in Service.svc file and access them in my XAML file to populate data in my controls. Combo's should have all the values in particular column of the Table(like All the Country Names should be Added to Combo Control) Also that after selecting All the combo's when a user clicks on a Select button the Selected Record should be displayed in DataGrid.

Thanks in Advance.

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These tutorials #1 and #2 can help you.