title: LINQ - UNION - remove duplicated based on a single column
body: <p>I have this linq query where i want to remove all the duplicates based on the column MAILADR (but keep the other columns):</p>
  
  <pre><code>    Dim dataObject = (From a In db.TABLE1 Select New With {
          .ID = a.BENUTZERNR,
          .MAILADR = a.EMAIL,
          .BENUTZERGRP = a.USRGRP
      }) _
      .Union(
          (From b In db.TABLE12 Select New With {
          .ID = b.ID,
          .MAILADR = b.MAILADR,
          .BENUTZERGRP = b.BENUTZERGRP 
      }) _
      )
  </code></pre>