Someone at work asked this question so I spent five minutes and banged out this code. If it helps one person, it probably will help many so here it is....
--------- Demo Removing Duplicate rows in a DataTable ----------------
using System;
using System.Data;
using System.Collections;
namespace Demo_DataTableRemoveDupRows
{
class Class1
{
[STAThread]
static void Main(string[] args)
{
// create an example datatable with duplicate rows
DataTable tbl = new DataTable();
tbl.Columns.Add("ColumnA");
tbl.Columns.Add("ColumnB");
tbl.Columns.Add("ColumnC");
for(int i = 0; i<10; i++)
{
DataRow nr = tbl.NewRow();
nr["ColumnA"] = "A" + i.ToString();
nr["ColumnB"] = "B" + i.ToString();
nr["ColumnC"] = "C" + i.ToString();
tbl.Rows.Add(nr);
// duplicate
nr = tbl.NewRow();
nr["ColumnA"] = "A" + i.ToString();
nr["ColumnB"] = "B" + i.ToString();
nr["ColumnC"] = "C" + i.ToString();
tbl.Rows.Add(nr);
}
PrintRows(tbl); // show table with duplicates
//Create an array of DataColumns to compare
//If these columns all match we consider the
//rows duplicate.
DataColumn[] keyColumns =
new DataColumn[]{tbl.Columns["ColumnA"],
tbl.Columns["ColumnA"]};
//remove the duplicates
RemoveDuplicates(tbl, keyColumns);
PrintRows(tbl); // show table again
Console.ReadLine(); // pause to view output
}
/// <summary>
/// Removes duplicate rows from given DataTable
/// </summary>
/// <param name="tbl">Table to scan for duplicate rows</param>
/// <param name="KeyColumns">An array of DataColumns
/// containing the columns to match for duplicates</param>
private static void RemoveDuplicates(DataTable tbl,
DataColumn[] keyColumns)
{
int rowNdx = 0;
while(rowNdx < tbl.Rows.Count-1)
{
DataRow[] dups = FindDups(tbl, rowNdx, keyColumns);
if(dups.Length>0)
{
foreach(DataRow dup in dups)
{
tbl.Rows.Remove(dup);
}
}
else
{
rowNdx++;
}
}
}
private static DataRow[] FindDups(DataTable tbl,
int sourceNdx,
DataColumn[] keyColumns)
{
ArrayList retVal = new ArrayList();
DataRow sourceRow = tbl.Rows[sourceNdx];
for(int i=sourceNdx + 1; i<tbl.Rows.Count; i++)
{
DataRow targetRow = tbl.Rows[i];
if(IsDup(sourceRow, targetRow, keyColumns))
{
retVal.Add(targetRow);
}
}
return (DataRow[]) retVal.ToArray(typeof(DataRow));
}
private static bool IsDup(DataRow sourceRow,
DataRow targetRow,
DataColumn[] keyColumns)
{
bool retVal = true;
foreach(DataColumn column in keyColumns)
{
retVal = retVal && sourceRow[column].Equals(targetRow[column]);
if(!retVal) break;
}
return retVal;
}
private static void PrintRows(DataTable tbl)
{
for(int i=0; i<tbl.Rows.Count; i++)
{
Console.WriteLine("row: {0}, ColumnA: {1}, ColumnB: {2}", i, tbl.Rows[i]["ColumnA"], tbl.Rows[i]["ColumnB"]);
}
}
}
}
--------- End Demo Code ----------------
Hope it helps someone....
-Andy