title: Concatenating rows in DataTable with specific condition
body: <p>I have a DataTable <code>dtTexts</code> like this</p>
  
  <pre><code>varenummer   text                   ID   Brand    LineNumber
   100         sometext-name          0     nike     0
   100         sometext -longdesc     2     nike     2
   100         sometext-shortdesc     1     nike     0
   100         sometext -longdesc-2   2      nike    0
  </code></pre>
  
  <p>I am converting this to another datatable like this</p>
  
  <pre><code>  var myRows = from myRow in dtTexts.AsEnumerable()
                           where myRow.Field&lt;string&gt;("Varenummer") == "100"
                           select myRow;
    DataRow newRow = dtFinalData.NewRow();
    bool firstRow = true;
              foreach (var drText in myRows)
              {
                  if (firstRow)
                  {
                      firstRow = false;
                      newRow["Varenummer"] = drText.ItemArray[0];
                      newRow["Brand"] = drText.ItemArray[3];
  
                  }
  
                  if (drText.ItemArray[2].ToString() == "0")
                  {
                      newRow["Varenavn"] = drText.ItemArray[1].ToString();
                  }
  
                  if (drText.ItemArray[2].ToString() == "1")
                  {
                      newRow["ShortDescription"] = Regex.Replace(drText.ItemArray[1].ToString(), "&lt;.+?&gt;", string.Empty);
  
                  }
                  if (drText.ItemArray[2].ToString() == "2")
                  {
                      newRow["LongDescription"] = Regex.Replace(drText.ItemArray[1].ToString(), "&lt;.+?&gt;", string.Empty);
  
                  }
  
              }
              dtFinalData.Rows.Add(newRow);
  </code></pre>
  
  <p>and getting an output like this</p>
  
  <pre><code>varenummer brand   varenavn          shortdescription     longDescription
  100         nike   sometext-name      sometext-shortdesc   sometext -longdesc 
  </code></pre>
  
  <p>Now the problem is I have two lines of Long description in my first dataTable. I want to concatenate them on the basis of <code>linenumber</code> column.So that I get an out put like </p>
  
  <pre><code> varenummer brand   varenavn          shortdescription     longDescription
      100     nike    sometext-name      sometext-shortdesc   sometext -longdesc+ sometext -longdesc-2
  </code></pre>
  
  <p>How can I do this in C#?</p>