title: Find Duplicate entries C#
body: <p>I am new to programming so this may seem somewhat straightforward, but I cannot seem to figure it out.</p>
  
  <p>I am trying to find duplicate values that are in a datatable in one column of the values. </p>
  
  <p>Here is what I was trying to do it with.</p>
  
  <pre><code>DataRow[] dupresults = dt.Select("PROV_NEW");
  TableIssues = string.Empty;
  DataTable dtTemp = dt.DefaultView.ToTable(true, "NEW_PROV");
  
  if (dupresults.Length == 0)
  {
      return true;
  }
  else
  {
      foreach (DataRow item in dupresults)
      {
          Console.WriteLine(item[1]);
          TableIssues += "Provider Code is not unique for " + item[1].ToString() + ". Revise non-unique codes.\r\n\n\n\n";
      }
      return false;
  }
  </code></pre>
  
  <p>Alright, but I am also having it search to make sure that there are no empty fields in PROV_NEW too. so I would not know where to put that. I am very new to c#. I just started last week. I am doing side projects for my father's company.</p>
  
  <pre><code>private bool ValidateTable(DataSets.Setup.SETUP_MWPROVDataTable dt, out string TableIssues)
      {
          try
          {
              //NewCode not used for other row
              DataRow[] result = dt.Select("PROV_NEW = ''");
              DataRow[] dupresults = dt.Select("PROV_NEW");
              TableIssues = string.Empty;
              DataTable dtTemp = dt.DefaultView.ToTable(true, "NEW_PROV");
  
  
  
              if (dupresults.Length == 0)
              {
  
                  return true;
              }
              else
              {
                  var duplicates = dt.AsEnumerable()
                 .Select(dr =&gt; dr.Field&lt;string&gt;("PROV_NEW"))
                 .GroupBy(x =&gt; x)
                 .Where(g =&gt; g.Count() &gt; 1)
                 .Select(g =&gt; g.Key)
                 .ToList();
  
                  foreach (DataRow item in dupresults)
                  {
                      Console.WriteLine(item[1]);
                      TableIssues += "Provider Code is not unique for " + item[1].ToString() + ". Revise non-unique codes.\r\n\n\n\n";
                  }
                  return false;
              }
  
  
              if (result.Length == 0)
              {
                  //TODO: Add Next Step for validation
  
                  return true;
  
              }
              else
              {
                  foreach (DataRow item in result)
                  {
                      Console.WriteLine(item[1]);
                      TableIssues += "Provider code " + item[1].ToString() + " is blank. Add new Provider code for " + item[1].ToString() +".\r\n\n\n";
                  }
  
  
                  return false;
              }
  
             }
          catch (Exception)
          {
  
              throw;
          }
      }
  
  
  }
  </code></pre>