C# DataTable Lamda GroupBy

 static void Main(string[] args)
 {
     DataTable dt = new DataTable();
     dt.Columns.Add("A");
     dt.Columns.Add("B");
     dt.Columns.Add("C");
     dt.Rows.Add("a1", "b1", "c1");
     dt.Rows.Add("a1", "b2", "c2");
     dt.Rows.Add("a2", "b3", "c3");
     dt.Rows.Add("a3", "b4", "c4");
     dt.Rows.Add("a1", "b5", "c5");
     dt.Rows.Add("a2", "b6", "c6");
     IEnumerable<IGrouping<string, DataRow>> result = dt.Rows.Cast<DataRow>().GroupBy<DataRow, string>(dr => dr["A"].ToString());//按A分组
     foreach (IGrouping<string, DataRow> ig in result)
     {
         Console.WriteLine("当A="+ig.Key + "：");
         Console.WriteLine("A".PadRight() + "B".PadRight() + "C".PadRight());
         Console.WriteLine("=====".PadRight() + "=====".PadRight() + "=====".PadRight());
         foreach (var dr in ig)
             Console.WriteLine(dr["A"].ToString().PadRight() + dr["B"].ToString().PadRight() + dr["C"].ToString().PadRight());

     }
     Console.Read();
 }