DataTable筛选，取前N条数据，获取指定列数据

谁借莪１个温暖的怀抱￠ 2022-02-27 14:38 255阅读 0赞

#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
            /// <summary>
            /// 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
            /// eg:SortExprDataTable(dt,"Sex='男'","Time Desc",1)
            /// </summary>
            /// <param name="dt">传入的DataTable</param>
            /// <param name="strExpr">筛选条件</param>
            /// <param name="strSort">排序条件</param>
            /// <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>
            public static DataTable SortDataTable(DataTable dt, string strExpr, string strSort, int mode)
            {
                switch (mode)
                {
                    case 1:
                        //方法一　直接用DefaultView按条件返回
                        dt.DefaultView.RowFilter = strExpr;
                        dt.DefaultView.Sort = strSort;
                        return dt;
                    case 2:
                        //方法二　DataTable筛选，排序返回符合条件行组成的新DataTable
                        DataTable dt1 = new DataTable();
                        DataRow[] GetRows = dt.Select(strExpr, strSort);
                        //复制DataTable dt结构不包含数据
                        dt1 = dt.Clone();
                        foreach (DataRow row in GetRows)
                        {
                            dt1.Rows.Add(row.ItemArray);
                        }
                        return dt1;
                    default:
                        return dt;
                }
            }
            #endregion

#region 获取DataTable前几条数据
            /// <summary>
            /// 获取DataTable前几条数据
            /// </summary>
            /// <param name="TopItem">前N条数据</param>
            /// <param name="oDT">源DataTable</param>
            /// <returns></returns>
            public static DataTable DtSelectTop(int TopItem, DataTable oDT)
            {
                if (oDT.Rows.Count < TopItem) return oDT;
    
                DataTable NewTable = oDT.Clone();
                DataRow[] rows = oDT.Select("1=1");
                for (int i = 0; i < TopItem; i++)
                {
                    NewTable.ImportRow((DataRow)rows[i]);
                }
                return NewTable;
            }
            #endregion
    
            #region 获取DataTable中指定列的数据
            /// <summary>
            /// 获取DataTable中指定列的数据
            /// </summary>
            /// <param name="dt">数据源</param>
            /// <param name="tableName">新的DataTable的名词</param>
            /// <param name="strColumns">指定的列名集合</param>
            /// <returns>返回新的DataTable</returns>
            public static DataTable GetTableColumn(DataTable dt, string tableName, params string[] strColumns)
            {
                DataTable dtn = new DataTable();
                if (dt == null)
                {
                    throw new ArgumentNullException("参数dt不能为null");
                }
                try
                {
                    dtn = dt.DefaultView.ToTable(tableName, true, strColumns);
                }
                catch (Exception e)
                {
                    throw new Exception(e.Message);
                }
                return dtn;
            }
            #endregion