string strSql;
string strCon;
strCon = "Data Source=RAYANEH-C5E4683\\SQLEXPRESS;Initial Catalog=Student1;Integrated Security=True";
SqlConnection  con = new SqlConnection(strCon);
con.Open();
strSql = "SELECT * FROM stTable";
SqlDataAdapter da = new SqlDataAdapter(strSql, con);
DataSet ds = new DataSet();
da.Fill(ds, "stTable");      
DataGrid1.DataBindings.Add(new Binding("DataSource", ds, "stTable"));
con.Close();
