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;
}

这里的链接下面

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

用于删除列中的重复项

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