DataTable相关操作，筛选，取前N条数据，获取指定列数据

 1         #region DataTable筛选，排序返回符合条件行组成的新DataTable或直接用DefaultView按条件返回

 2         /// <summary>

 3         /// DataTable筛选，排序返回符合条件行组成的新DataTable或直接用DefaultView按条件返回

 4         /// eg:SortExprDataTable(dt,"Sex='男'","Time Desc",1)

 5         /// </summary>

 6         /// <param name="dt">传入的DataTable</param>

 7         /// <param name="strExpr">筛选条件</param>

 8         /// <param name="strSort">排序条件</param>

 9         /// <param name="mode">1,直接用DefaultView按条件返回,效率较高;2,DataTable筛选，排序返回符合条件行组成的新DataTable</param>

10         public static DataTable SortDataTable(DataTable dt, string strExpr, string strSort, int mode)

11         {

12             switch (mode)

13             {

14                 case 1:

15                     //方法一　直接用DefaultView按条件返回

16                     dt.DefaultView.RowFilter = strExpr;

17                     dt.DefaultView.Sort = strSort;

18                     return dt;

19                 case 2:

20                     //方法二　DataTable筛选，排序返回符合条件行组成的新DataTable

21                     DataTable dt1 = new DataTable();

22                     DataRow[] GetRows = dt.Select(strExpr, strSort);

23                     //复制DataTable dt结构不包含数据

24                     dt1 = dt.Clone();

25                     foreach (DataRow row in GetRows)

26                     {

27                         dt1.Rows.Add(row.ItemArray);

28                     }

29                     return dt1;

30                 default:

31                     return dt;

32             }

33         }

34         #endregion

35         #region 获取DataTable前几条数据

36         /// <summary>

37         /// 获取DataTable前几条数据

38         /// </summary>

39         /// <param name="TopItem">前N条数据</param>

40         /// <param name="oDT">源DataTable</param>

41         /// <returns></returns>

42         public static DataTable DtSelectTop(int TopItem, DataTable oDT)

43         {

44             if (oDT.Rows.Count < TopItem) return oDT;

45 

46             DataTable NewTable = oDT.Clone();

47             DataRow[] rows = oDT.Select("1=1");

48             for (int i = 0; i < TopItem; i++)

49             {

50                 NewTable.ImportRow((DataRow)rows[i]);

51             }

52             return NewTable;

53         }

54         #endregion

55 

56         #region 获取DataTable中指定列的数据

57         /// <summary>

58         /// 获取DataTable中指定列的数据

59         /// </summary>

60         /// <param name="dt">数据源</param>

61         /// <param name="tableName">新的DataTable的名词</param>

62         /// <param name="strColumns">指定的列名集合</param>

63         /// <returns>返回新的DataTable</returns>

64         public static DataTable GetTableColumn(DataTable dt, string tableName, params string[] strColumns)

65         {

66             DataTable dtn = new DataTable();

67             if (dt == null)

68             {

69                 throw new ArgumentNullException("参数dt不能为null");

70             }

71             try

72             {

73                 dtn = dt.DefaultView.ToTable(tableName, true, strColumns);

74             }

75             catch (Exception e)

76             {

77                 throw new Exception(e.Message);

78             }

79             return dtn;

80         }

81         #endregion