版權宣告：本文為博主原創文章，引用如需標註必須出處  https://blog.csdn.net/qq_37227093/article/details/84335798

        /// <summary>
        /// 從DataGridView的Rows中篩選指定列
        /// </summary>
        public static List<T> UAllList<T>(this DataGridView dgv, string columnName)
        {
            if (dgv.Rows.Count == 0) return null;

            return (from DataGridViewRow dgvr in dgv.Rows
                select UValueConvert.ConvertByObj<T>(dgvr.Cells[columnName].Value)).Distinct().ToList();
        }

        /// <summary>
        /// 從DataGridView的SelectedRows中篩選指定列
        /// </summary>
        public static List<T> USelectedList<T>(this DataGridView dgv, string columnName)
        {
            if (dgv.SelectedRows.Count == 0) return null;

            return (from DataGridViewRow dgvr in dgv.SelectedRows
                where !string.IsNullOrEmpty(dgvr.Cells[columnName].Value.ToString())
                select UValueConvert.ConvertByObj<T>(dgvr.Cells[columnName].Value)).Distinct().ToList();
        }

        /// <summary>
        /// 獲取選中行或選中單元格中的值
        /// </summary>
        public static T USingle<T>(this DataGridView dgv, string columnName = null)
        {
            var cell = columnName == null ? dgv.SelectedCells[0] : dgv.SelectedRows[0].Cells[columnName];
            return UValueConvert.ConvertByObj<T>(cell.Value);
        }

注：     UValueConvert.ConvertByObj <T>是自己封裝好的型別轉換