[C#] DataTable operation summary (continuous update)

1. DataTable grouping operation

var grow = dt.Select().GroupBy((row1) =>
{
    return new
    {
        // grouped fields
        fieldA = row1["a"].ToString(),
        fieldB = row1["b"].ToString()
    };
}).ToList();

foreach(var item in grow)
{
    string aa = item.Key.fieldA;
    string bb = item.Key.fieldB;

    IEnumerator<DataRow> rows = item.GetEnumerator();//var rows = item.GetEnumerator(); 也可以
    while(rows.MoveNext())
    {
      DataRow dr = rows.Current;

    }
}