Best way to remove duplicate entries from a data table

Question

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

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You can use the DefaultView ToTable method of a DataTable to do the filtering like this  adapt to 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

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To eliminate Duplicate rows        private void RemoveDuplicates DataTable dt                 if  dt Rows Count  gt  0                        for  int i   dt Rows Count - 1  i  gt   0  i--                                if  i    0                                        break                                    for  int j   i - 1  j  gt   0  j--                                        if  Convert ToInt32 dt Rows i   ID       Convert ToInt32 dt Rows j   ID     amp  amp  dt Rows i   Name   ToString      dt Rows j   Name   ToString                                                  dt Rows i  Delete                            break                                                                    dt AcceptChanges

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Do dtEmp on your current working DataTable   DataTable distinctTable   dtEmp DefaultView ToTable    distinct   true     It s nice

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Completely distinct rows    public static DataTable Dictinct this dt    gt  dt DefaultView ToTable true     Distinct by particular row s   Note that the columns mentioned in  distinctCulumnNames  will be returned in resulting DataTable    public static DataTable Dictinct this dt  params string   distinctColumnNames    gt   dt DefaultView ToTable true  distinctColumnNames     Distinct by particular column  preserves all columns in given DataTable    public static void Distinct this DataTable dataTable  string distinctColumnName        var distinctResult   new DataTable        distinctResult Merge                        GroupBy row   gt  row Field lt object gt  distinctColumnName                         Select group   gt  group First                          CopyToDataTable                       if  distinctResult DefaultView Count  lt  dataTable DefaultView Count                dataTable Clear            dataTable Merge distinctResult           dataTable AcceptChanges

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A simple way would be    var newDt  dt AsEnumerable                     GroupBy x   gt  x Field lt int gt   ColumnName                      Select y   gt  y First                      CopyToDataTable

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There is a simple way using Linq GroupBy Method   var duplicateValues   dt AsEnumerable              GroupBy row   gt  row 0              Where group   gt   group Count      1    group Count    gt  1              Select g   gt  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

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Heres a easy and fast way using AsEnumerable   Distinct   private DataTable RemoveDuplicatesRecords DataTable dt          Returns just 5 unique rows     var UniqueRows   dt AsEnumerable   Distinct DataRowComparer Default       DataTable dt2   UniqueRows CopyToDataTable        return dt2     My Blog Article  Remove duplicate rows from datatable

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Remove Duplicates  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  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  http   dotnetguts blogspot com 2007 02 removing-duplicate-records-from html

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

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In order to distinct all datatable columns  you can easily retrieve the names of the columns in a string array  public static DataTable RemoveDuplicateRows this DataTable dataTable        List lt string gt  columnNames   new List lt string gt         foreach  DataColumn col in dataTable Columns                columnNames Add col ColumnName             return dataTable DefaultView ToTable true  columnNames Select c   gt  c ToString    ToArray         As you can notice  I thought of using it as an extension to DataTable class

[c#] Best way to remove duplicate entries from a data table

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