Linq 和DefaultView兩種方法去掉DataTable 里的重復行

在做項目的時候經常會遇到DataTable 里的數據重復，或者合並兩個DataTable后有數據重復

一般我們是想把重復的刪除掉，還有其它的方式實現比如用Linq和DataTable的DefaultView來去掉重復的行

做了一個小例子，很簡單的大家可以看一下，最后有完整的代碼

也可以直接下載工程：RemoveDupRowDemo.rar

先看一下效果

先寫一個數據源

DataTable _dt = new DataTable();
_dt.Columns.Add("id", typeof(int));
_dt.Columns.Add("name", typeof(string));
_dt.Columns.Add("address", typeof(string));

DataRow _dr = _dt.NewRow();
_dr["id"] = 1;
_dr["name"] = "lipeng";
_dr["address"] = "DongXiaoKou";
_dt.Rows.Add(_dr);
_dt.Rows.Add(_dr.ItemArray);
_dt.Rows.Add(_dr.ItemArray);
_dr = _dt.NewRow();
_dr["id"] = 2;
_dr["name"] = "xiaoNa";
_dr["address"] = "DongXiaoKou";
_dt.Rows.Add(_dr);
_dr = _dt.NewRow();
_dr["id"] = 3;
_dr["name"] = "BingLi";
_dr["address"] = "TianTongYuan";
_dt.Rows.Add(_dr);
_dt.Rows.Add(_dr.ItemArray);
Console.WriteLine("--------------------原來有重復數據的Table----------------------");
_dt.AsEnumerable().ToList().ForEach(
x =>
{
Console.WriteLine(x["id"].ToString() + " " + x["name"].ToString() + " " + x["address"].ToString());
});

Console.WriteLine();

先用Linq的Distinct方法實現，因為每行有好多列，要實現IEqualityComparer<T>接口

public class DataTableRowCompare : IEqualityComparer<DataRow>
    {

        #region IEqualityComparer<DataRow> 成員

        public bool Equals(DataRow x, DataRow y)
        {
            return (x.Field<int>("id") == y.Field<int>("id"));
        }

        public int GetHashCode(DataRow obj)
        {
            return obj.ToString().GetHashCode();
        }

        #endregion
    }

在Main里實現 吧

 Console.WriteLine("--------------------用Linq去重復后的Table----------------------");

            var _comPresult = _dt.AsEnumerable().Distinct(new DataTableRowCompare());
            DataTable _resultDt = _comPresult.CopyToDataTable();

            _resultDt.AsEnumerable().ToList().ForEach(
               x =>
               {
                   Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
               });

            Console.WriteLine();

 

用Table里的DefalutView實面DefalutView有個ToTable方法可以做到去重復

  Console.WriteLine("--------------------用DefaultView去重復后的Table----------------------");
            DataTable _dtDefalut = _dt.DefaultView.ToTable(true, "id", "name", "address");


            _dtDefalut.AsEnumerable().ToList().ForEach(
              x =>
              {
                  Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
              });

            Console.ReadLine();

　　

個人感覺 還是Linq的好一點，用DefaultView如果你的列少的話還好些，如果列太多的話工作量就太大了

 

下面給一下完整的代碼 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;

namespace RemoveDupRowDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable _dt = new DataTable();
            _dt.Columns.Add("id", typeof(int));
            _dt.Columns.Add("name", typeof(string));
            _dt.Columns.Add("address", typeof(string));

            DataRow _dr = _dt.NewRow();
            _dr["id"] = 1;
            _dr["name"] = "lipeng";
            _dr["address"] = "DongXiaoKou";
            _dt.Rows.Add(_dr);
            _dt.Rows.Add(_dr.ItemArray);
            _dt.Rows.Add(_dr.ItemArray);
            _dr = _dt.NewRow();
            _dr["id"] = 2;
            _dr["name"] = "xiaoNa";
            _dr["address"] = "DongXiaoKou";
            _dt.Rows.Add(_dr);
            _dr = _dt.NewRow();
            _dr["id"] = 3;
            _dr["name"] = "BingLi";
            _dr["address"] = "TianTongYuan";
            _dt.Rows.Add(_dr);
            _dt.Rows.Add(_dr.ItemArray);
            Console.WriteLine("--------------------原來有重復數據的Table----------------------");
            _dt.AsEnumerable().ToList().ForEach(
                x =>
                {
                    Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
                });


            Console.WriteLine();

            Console.WriteLine("--------------------用Linq去重復后的Table----------------------");

            var _comPresult = _dt.AsEnumerable().Distinct(new DataTableRowCompare());
            DataTable _resultDt = _comPresult.CopyToDataTable();

            _resultDt.AsEnumerable().ToList().ForEach(
               x =>
               {
                   Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
               });

            Console.WriteLine();

            Console.WriteLine("--------------------用DefaultView去重復后的Table----------------------");
            DataTable _dtDefalut = _dt.DefaultView.ToTable(true, "id", "name", "address");


            _dtDefalut.AsEnumerable().ToList().ForEach(
              x =>
              {
                  Console.WriteLine(x["id"].ToString() + "    " + x["name"].ToString() + "   " + x["address"].ToString());
              });

            Console.ReadLine();
        }
    }

    public class DataTableRowCompare : IEqualityComparer<DataRow>
    {

        #region IEqualityComparer<DataRow> 成員

        public bool Equals(DataRow x, DataRow y)
        {
            return (x.Field<int>("id") == y.Field<int>("id"));
        }

        public int GetHashCode(DataRow obj)
        {
            return obj.ToString().GetHashCode();
        }

        #endregion
    }
}

　　

工程：RemoveDupRowDemo.rar