C#获取DataTable的前N行数据然后按指定字段排序

获取DataTable的前N行数据然后按指定字段排序

可以使用以下三种代码：

第一种：使用Linq

DataTable dtLast = dataTable.AsEnumerable().Take(count).OrderBy(dataRow => Convert.ToInt32(dataRow["Sequence"])).CopyToDataTable();

第二种：使用默认视图的Sort属性：

            DataTable dtLast = dataTable.AsEnumerable().Take(count).CopyToDataTable();dtLast.DefaultView.Sort = "Sequence asc";//逆序为Sequence descdtLast = dtLast.DefaultView.ToTable();

第三种：使用循环迭代

            DataTable dtLast = dataTable.Clone();//克隆表结构，行数为0for (int i = 0; i < getCount; i++){dtLast.Rows.Add(dataTable.Rows[i].ItemArray);}//按照Sequence进行排序DataRow[] array = dtLast.Select("1=1", "Sequence");dtLast = array.CopyToDataTable();

整体测试程序如下：

控制台应用程序FilterDataTableDemo

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace FilterDataTableDemo
{class Program{static void Main(string[] args){int topCount = 5;DataTable dataTable = GetDataTable();PrintDataTable(dataTable);Console.WriteLine($"----------【使用Linq】打印DataTable的前【{topCount}】行并按Sequence顺序排序----------");DataTable dtLinq = GetTopDataAndOrderUseLinq(dataTable, topCount);PrintDataTable(dtLinq);Console.WriteLine($"--------【使用视图View】打印DataTable的前【{topCount}】行并按Sequence顺序排序--------");DataTable dtView = GetTopDataAndOrderUseView(dataTable, topCount);PrintDataTable(dtView);Console.WriteLine($"--------【使用循环迭代】打印DataTable的前【{topCount}】行并按Sequence顺序排序--------");DataTable dtIterator = GetTopDataAndOrderUseIterator(dataTable, topCount);PrintDataTable(dtIterator);Console.ReadLine();}/// <summary>/// 使用Linq获取前N行数据并排序/// </summary>/// <param name="dataTable"></param>/// <param name="count"></param>/// <returns></returns>static DataTable GetTopDataAndOrderUseLinq(DataTable dataTable, int count) {DataTable dtLast = dataTable.AsEnumerable().Take(count).OrderBy(dataRow => Convert.ToInt32(dataRow["Sequence"])).CopyToDataTable();return dtLast;}/// <summary>/// 使用视图的默认排序/// </summary>/// <param name="dataTable"></param>/// <param name="count"></param>/// <returns></returns>static DataTable GetTopDataAndOrderUseView(DataTable dataTable, int count){DataTable dtLast = dataTable.AsEnumerable().Take(count).CopyToDataTable();dtLast.DefaultView.Sort = "Sequence asc";//逆序为Sequence descdtLast = dtLast.DefaultView.ToTable();return dtLast;}/// <summary>/// 使用循环迭代获取前N行数据并排序/// </summary>/// <param name="dataTable"></param>/// <param name="count"></param>/// <returns></returns>static DataTable GetTopDataAndOrderUseIterator(DataTable dataTable, int count){//考虑到 获取的行数比数据表本身的行数还要多，这里取较小值int getCount = Math.Min(dataTable.Rows.Count, count);DataTable dtLast = dataTable.Clone();//克隆表结构，行数为0for (int i = 0; i < getCount; i++){dtLast.Rows.Add(dataTable.Rows[i].ItemArray);}//按照Sequence进行排序DataRow[] array = dtLast.Select("1=1", "Sequence");dtLast = array.CopyToDataTable();return dtLast;}/// <summary>/// 生成测试内存表/// </summary>/// <returns></returns>static DataTable GetDataTable() {DataTable dt = new DataTable("Test");dt.Columns.Add("CoreId", typeof(int));dt.Columns.Add("Sequence", typeof(int));dt.Columns.Add("TestName", typeof(string));dt.Rows.Add(10, 5, "云天河");dt.Rows.Add(9, 4, "柳梦璃");dt.Rows.Add(8, 3, "韩菱纱");dt.Rows.Add(7, 2, "慕容紫英");dt.Rows.Add(6, 1, "璇玑");dt.Rows.Add(5, 5, "怀朔");dt.Rows.Add(4, 4, "云天青");dt.Rows.Add(3, 3, "夙玉");dt.Rows.Add(2, 2, "夙瑶");dt.Rows.Add(1, 1, "玄霄");return dt;}/// <summary>/// 打印内存数据表信息/// </summary>/// <param name="dataTable"></param>static void PrintDataTable(DataTable dataTable) {for (int i = 0; i < dataTable.Rows.Count; i++){Console.WriteLine(string.Join(",", dataTable.Rows[i].ItemArray));}}}
}

程序运行如图：