Linq 和DefaultView两种方法去掉DataTable 里的重复行
在做项目的时候经常会遇到DataTable 里的数据重复，或者合并两个DataTable后有数据重复
一般我们是想把重复的删除掉，还有其它的方式实现比如用Linq和DataTable的DefaultView来去掉重复的行
做了一个小例子，很简单的大家可以看一下，最后有完整的代码
也可以直接下载工程：RemoveDupRowDemo.rar
先看一下效果
先写一个数据源
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("--------------------原来有重复数据的Table----------------------");
_dt.AsEnumerable().ToList().ForEach(
x =>
{
Console.WriteLine(x["id"].ToString() + " " + x["name"].ToString() + " " + x["address"].ToString());
});
Console.WriteLine();
先用Linq的Distinct方法实现，因为每行有好多列，要实现IEqualityComparer<T>接口
public class DataTableRowCompare : IEqualityComparer<DataRow>
{
#region IEqualityComparer<DataRow> 成员
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里实现 吧
Console.WriteLine("--------------------用Linq去重复后的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实面DefalutView有个ToTable方法可以做到去重复
Console.WriteLine("--------------------用DefaultView去重复后的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();
个人感觉 还是Linq的好一点，用DefaultView如果你的列少的话还好些，如果列太多的话工作量就太大了
下面给一下完整的代码
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("--------------------原来有重复数据的Table----------------------");
_dt.AsEnumerable().ToList().ForEach(
x =>
{
Console.WriteLine(x["id"].ToString() + " " + x["name"].ToString() + " " + x["address"].ToString());
});
Console.WriteLine();
Console.WriteLine("--------------------用Linq去重复后的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去重复后的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> 成员
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
}
}