DataTable 按照字段分组

        public static DataTable[] SplitDataTable(DataTable mainTable, string keyField)
        {
            var groups = mainTable.AsEnumerable()
                .GroupBy(row => row.Field<string>(keyField))
                .Select(group =>
                {
                    var dt = mainTable.Clone();
                    dt.TableName = group.Key;
                    foreach (var row in group)
                    {
                        dt.ImportRow(row);
                    }
                    return dt;
                })
                .ToArray();

            return groups;
        }