using in C# used for many ways.. as word keyword using means using.. on start when we used using system; that means there is a DLL of name System in which all main functions are stored and we use it to short our code...
system.WriteLine("Andy");
but when we use system above then we can write it as
WriteLine("Andy");
more over in SQLserver when we use using connection it means after we use data from database by using command connection will itself close. it is very useful for a coder who wants to save its time
