瓶水相逢 - 艾小克

   1:  using System.Data;

   2:  using System.Linq;

   3:   

   4:  /// <summary>

   5:  /// DataTable 的擴充方法類別

   6:  /// </summary>

   7:  public static class DataTableExtensionMethods

   8:  {

   9:      /// <summary>

  10:      /// DataTable 分頁與排序

  11:      /// </summary>

  12:      /// <param name="dt">DataTable 資料來源</param>

  13:      /// <param name="PageIndex">第 n 頁(Index 由 1 開始)</param>

  14:      /// <param name="PageSize">每頁資料筆數</param>

  15:      /// <param name="SortField">排序的欄位名稱(大小寫不分)</param>

  16:      /// <param name="IsDescending">設定 true 則為 Descending；否則為 Aescending。</param>

  17:      /// <returns>分頁與排序後的 DataTable</returns>

  18:      public static DataTable PagingAndSorting(this DataTable dt, int PageIndex, int PageSize, string SortField, bool IsDescending)

  19:      {

  20:          // 檢查 頁數不是為正數 或是 單頁資料筆數不是正數

  21:          if (PageIndex <= 0 || PageSize <= 0)

  22:          {

  23:              dt.Rows.Clear();

  24:              return dt;

  25:          }

  26:   

  27:          // 計算跳過多少筆數

  28:          var skip = (PageIndex - 1) * PageSize;

  29:   

  30:          // (1) 略過筆數超過總筆數 (頁數錯誤) (2) 不包含 SortField 欄位

  31:          if (skip >= dt.Rows.Count || dt.Columns.Contains(SortField) == false)

  32:          {

  33:              dt.Rows.Clear();

  34:              return dt;

  35:          }

  36:   

  37:          // 由大到小排序 DESC

  38:          if (IsDescending)

  39:          {

  40:              return dt.AsEnumerable().OrderByDescending(dr => dr[SortField]).Skip(skip).Take(PageSize).CopyToDataTable();

  41:          }

  42:   

  43:          // 由小到大排序 ASC

  44:          return dt.AsEnumerable().OrderBy(dr => dr[SortField]).Skip(skip).Take(PageSize).CopyToDataTable();

  45:      }

  46:  }