基于多列从数据表中删除重复行 [英] Removal of Duplicate Rows from Data table Based on Multiple columns

问题描述

我有数据表，其中包含许多重复行，我需要根据多个列从数据表中过滤这些行，以在结果数据表中获取不同的行....

I have data table which contains many duplicate rows i need to filter those rows from data table based upon multiple columns to get distinct rows in resultant data table....

Barcode Itemid PacktypeId

1      100      1

1      100      2

1      100      3

1      100      1

1      100      3

只需要包含packtypeid的行1,2,3剩余的第4行和第5行应该删除



我尝试过使用两种方法，但没有一种没有转向更好的结果



数据表包含10多列但是唯一列是条形码，ItemID，PackTypeID



方法-1：

need only rows which contains packtypeid 1,2,3 remaining 4th and 5th row should be removed

I have tried using two methods but none didn't turns for better result

Data table contains more than 10 columns but unique column's is "Barcode", "ItemID", "PackTypeID"

Method-1:

dt_Barcode = dt_Barcode.DefaultView.ToTable(true, "Barcode", "ItemID", "PackTypeID");

上面的方法过滤器是行，但它只返回列3列值我需要整个10列值。



方法-2：

The above method filter's the rows but it returns columns only 3 column values i need entire 10 column values.

Method-2:

List<string> keyColumns = new List<string>();
keyColumns.Add("Barcode");
keyColumns.Add("ItemID");
keyColumns.Add("PackTypeID");   
RemoveDuplicates(DataTable table, List<string> keyColumns)
{
	var uniqueness = new HashSet<string>();
	StringBuilder sb = new StringBuilder();
	int rowIndex = 0;
	DataRow row;
	DataRowCollection rows = table.Rows;             
	int i = rows.Count;
	while (rowIndex < i)
	{
	row = rows[rowIndex];
	sb.Length = 0;
	foreach (string colname in keyColumns)
	{
		sb.Append(row[colname]);
		sb.Append("|");
	}
	
	if (uniqueness.Contains(sb.ToString()))
	{
		rows.Remove(row);
	}
	else
	{
		uniqueness.Add(sb.ToString());
		rowIndex++;
	}
}

Above Method返回异常，就像位置5处没有行一样

The Above Method returns exception like there is no rows at position 5

推荐答案

尝试使用LINQ

try with LINQ

dt_Barcode = dt_Barcode.AsEnumerable()
            .GroupBy(r => new { Itemid = r.Field<int>("Itemid"), PacktypeId = r.Field<int>("PacktypeId")})
            .Select(g => g.First())
            .CopyToDataTable();

样本测试代码：

Sample Test Code:

void Main()
{
    DataTable dt_Barcode =GetTable();
	dt_Barcode = dt_Barcode.AsEnumerable()
            .GroupBy(r => new { Itemid = r.Field<int>("Itemid"), PacktypeId = r.Field<int>("PacktypeId")})
            .Select(g => g.First())
            .CopyToDataTable();
}

DataTable GetTable()
{
	DataTable table = new DataTable();
	table.Columns.Add("Barcode", typeof(int));
	table.Columns.Add("Itemid", typeof(int));
	table.Columns.Add("PacktypeId", typeof(int));
	table.Rows.Add(1,100,1);
	table.Rows.Add(1,100,2);
	table.Rows.Add(1,100,3);
	table.Rows.Add(1,100,1);
	table.Rows.Add(1,100,3);
	return table;
}

问题的示例代码。

列表< items> arritems = new List< items>（）;

items item = new items（）;

items item1 = new items（）;

items item2 = new items（）;

items item3 = new items（）;

items item4 = new items（）;

item。条形码= 1;

item.itemid = 100;

item.packtypeid = 1;



item1。条形码= 1;

item1.itemid = 100;

item1.packtypeid = 2;



item2。条形码= 1;

item2.itemid = 100;

item2.packtypeid = 3;



item3。条形码= 1;

item3.itemid = 100;

item3.packtypeid = 1;



item4。条形码= 1;

item4.itemid = 100;

item4.packtypeid = 3;





arritems.Add（item）;

arritems.Add（item1）;

arritems.Add（item2）;

arritems.Add（item3）;

arritems.Add（item4）;



var distinctList = arritems.Select（ x => new {x.itemid，x.packtypeid}）。Distinct（）。ToList（）;

Example code for your problem.
List<items> arritems = new List<items>();
items item = new items();
items item1 = new items();
items item2 = new items();
items item3 = new items();
items item4 = new items();
item.barcode = 1;
item.itemid = 100;
item.packtypeid = 1;

item1.barcode = 1;
item1.itemid = 100;
item1.packtypeid = 2;

item2.barcode = 1;
item2.itemid = 100;
item2.packtypeid = 3;

item3.barcode = 1;
item3.itemid = 100;
item3.packtypeid = 1;

item4.barcode = 1;
item4.itemid = 100;
item4.packtypeid = 3;


arritems.Add(item);
arritems.Add(item1);
arritems.Add(item2);
arritems.Add(item3);
arritems.Add(item4);

var distinctList = arritems.Select(x => new{x.itemid , x.packtypeid}).Distinct().ToList();

public class items
    {
        public int barcode;
        public int itemid;
        public int packtypeid;
    }

在其他论坛和CodeProject本身已经讨论了很多次。



请看下面的链接：



http://stackoverflow.com/questions/1199176/how-to-select-distinct-rows-in-a-datatable-and-store -into-an-array [ ^ ]



http://stackoverflow.com/questions/17221561/datatable-distinct-rows [ ^ ]



ht tp：//stackoverflow.com/questions/12723289/linq-datatable-select-distinct-rows [ ^ ]



根据DataTable的指定字段选择DISTINCT记录 [ ^ ]

This has been discussed so many times on other forums and CodeProject itself.

Look at the links below:

http://stackoverflow.com/questions/1199176/how-to-select-distinct-rows-in-a-datatable-and-store-into-an-array[^]

http://stackoverflow.com/questions/17221561/datatable-distinct-rows[^]

http://stackoverflow.com/questions/12723289/linq-datatable-select-distinct-rows[^]

Select DISTINCT records based on specified fields for DataTable [^]

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