从数据表中删除重复条目的最佳方法

What is the best way to remove duplicate entries from a Data Table?

从数据表中删除重复条目的最佳方法是什么？

9 个解决方案

#1

Remove Duplicates

删除重复项

public DataTable RemoveDuplicateRows(DataTable dTable, string colName)
{
   Hashtable hTable = new Hashtable();
   ArrayList duplicateList = new ArrayList();

   //Add list of all the unique item value to hashtable, which stores combination of key, value pair.
   //And add duplicate item value in arraylist.
   foreach (DataRow drow in dTable.Rows)
   {
      if (hTable.Contains(drow[colName]))
         duplicateList.Add(drow);
      else
         hTable.Add(drow[colName], string.Empty); 
   }

   //Removing a list of duplicate items from datatable.
   foreach (DataRow dRow in duplicateList)
      dTable.Rows.Remove(dRow);

   //Datatable which contains unique records will be return as output.
      return dTable;
}

Here Links below

这里链接如下

http://www.dotnetspider.com/resources/4535-Remove-duplicate-records-from-table.aspx

http://www.dotnetspark.com/kb/94-remove-duplicate-rows-value-from-datatable.aspx

For remove duplicates in column

用于删除列中的重复项

http://dotnetguts.blogspot.com/2007/02/removing-duplicate-records-from.html

#2

Do dtEmp on your current working DataTable:

对你当前工作的DataTable执行dtEmp：

DataTable distinctTable = dtEmp.DefaultView.ToTable( /*distinct*/ true);

It's nice.

这真好。

#3

This post is regarding fetching only Distincts rows from Data table on basis of multiple Columns.

这篇文章是关于从多个Columns中仅从Data表中获取Distincts行。

Public coid removeDuplicatesRows(DataTable dt)
{
  DataTable uniqueCols = dt.DefaultView.ToTable(true, "RNORFQNo", "ManufacturerPartNo",  "RNORFQId", "ItemId", "RNONo", "Quantity", "NSNNo", "UOMName", "MOQ", "ItemDescription");
}

You need to call this method and you need to assign value to datatable. In Above code we have RNORFQNo , PartNo,RFQ id,ItemId, RNONo, QUantity, NSNNO, UOMName,MOQ, and Item Description as Column on which we want distinct values.

您需要调用此方法，并且需要为datatable分配值。在上面的代码中，我们有RNORFQNo，PartNo，RFQ id，ItemId，RNONo，QUANTity，NSNNO，UOMName，MOQ和Item Description作为我们想要不同值的列。

#4

A simple way would be:

一个简单的方法是：

 var newDt= dt.AsEnumerable()
                 .GroupBy(x => x.Field<int>("ColumnName"))
                 .Select(y => y.First())
                 .CopyToDataTable();

#5

There is a simple way using Linq GroupBy Method.

使用Linq GroupBy方法有一种简单的方法。

var duplicateValues = dt.AsEnumerable() 

        .GroupBy(row => row[0]) 

        .Where(group => (group.Count() == 1 || group.Count() > 1)) 

        .Select(g => g.Key); 



foreach (var d in duplicateValues)

        Console.WriteLine(d);

See more at: http://www.dotnetlines.com/Blogs/tabid/85/EntryId/49/Remove-duplicate-rows-from-a-DataTable-using-LINQ.aspx
详情请见：http：//www.dotnetlines.com/Blogs/tabid/85/EntryId/49/Remove-duplicate-rows-from-a-DataTable-using-LINQ.aspx

#6

Heres a easy and fast way using AsEnumerable().Distinct()

使用AsEnumerable（）是一种简单快捷的方式.Difininct（）

private DataTable RemoveDuplicatesRecords(DataTable dt)
{
    //Returns just 5 unique rows
    var UniqueRows = dt.AsEnumerable().Distinct(DataRowComparer.Default);
    DataTable dt2 = UniqueRows.CopyToDataTable();
    return dt2;
}

CLICK to visit my blog for more Detail

点击访问我的博客了解更多详情

#7

    /* To eliminate Duplicate rows */
    private void RemoveDuplicates(DataTable dt)
    {

        if (dt.Rows.Count > 0)
        {
            for (int i = dt.Rows.Count - 1; i >= 0; i--)
            {
                if (i == 0)
                {
                    break;
                }
                for (int j = i - 1; j >= 0; j--)
                {
                    if (Convert.ToInt32(dt.Rows[i]["ID"]) == Convert.ToInt32(dt.Rows[j]["ID"]) && dt.Rows[i]["Name"].ToString() == dt.Rows[j]["Name"].ToString())
                    {
                        dt.Rows[i].Delete();
                        break;
                    }
                }
            }
            dt.AcceptChanges();
        }
    }

#8

You can use the DefaultView.ToTable method of a DataTable to do the filtering like this (adapt to C#):

您可以使用DataTable的DefaultView.ToTable方法进行这样的过滤（适应C＃）：

 Public Sub RemoveDuplicateRows(ByRef rDataTable As DataTable)
    Dim pNewDataTable As DataTable
    Dim pCurrentRowCopy As DataRow
    Dim pColumnList As New List(Of String)
    Dim pColumn As DataColumn

    'Build column list
    For Each pColumn In rDataTable.Columns
        pColumnList.Add(pColumn.ColumnName)
    Next

    'Filter by all columns
    pNewDataTable = rDataTable.DefaultView.ToTable(True, pColumnList.ToArray)

    rDataTable = rDataTable.Clone

    'Import rows into original table structure
    For Each pCurrentRowCopy In pNewDataTable.Rows
        rDataTable.ImportRow(pCurrentRowCopy)
    Next
End Sub

#9

Completely distinct rows:

完全不同的行：

public static DataTable Dictinct(this dt) => dt.DefaultView.ToTable(true);

Distinct by particular row(s) (Note that the columns mentioned in "distinctCulumnNames" will be returned in resulting DataTable):

区别于特定行（请注意，“distinctCulumnNames”中提到的列将在结果DataTable中返回）：

public static DataTable Dictinct(this dt, params string[] distinctColumnNames) => 
dt.DefaultView.ToTable(true, distinctColumnNames);

Distinct by particular column (preserves all columns in given DataTable):

与特定列不同（保留给定DataTable中的所有列）：

public static void Distinct(this DataTable dataTable, string distinctColumnName)
{
    var distinctResult = new DataTable();
    distinctResult.Merge(
                     .GroupBy(row => row.Field<object>(distinctColumnName))
                     .Select(group => group.First())
                     .CopyToDataTable()
            );

    if (distinctResult.DefaultView.Count < dataTable.DefaultView.Count)
    {
        dataTable.Clear();
        dataTable.Merge(distinctResult);
        dataTable.AcceptChanges();
    }
}

#1