title: UPDATE statement on JOIN runs with no errors, but nothing happens
body: <p>I am trying to UPDATE a table based off of a date range from two separate tables (table person and invoice) and to all that have the source "purch" (from person table).  Please see below:</p>
  
  <pre><code>UPDATE Person
  SET Person.pers_ThankYou_Letter='Y',
      Person.pers_newpurch='recievedLetter',
      Person.pers_update='2016-05-09' 
  FROM Person T1
  INNER JOIN dbo.invoice T2
  ON T1.Pers_PersonId = T2.invoice_personid
  WHERE
      T1.Pers_CreateDate &gt;= '2016-02-16'
  AND
  T2.invoice_InvDate &gt; '2016-02-16'
  AND
  T1.Pers_Source = 'Purch';
  </code></pre>
  
  <p>I am using SQL Server Management Studio 2005. I tried various other ways going </p>
  
  <pre><code>SELECT * FROM Person
  UPDATE Invoice a JOIN Person b ON (a.personid = b.Pers_PersonId)
      SET pers_ThankYou, 
      Person.pers_update='2016-05-09',
      pers_newpurch='recievedLetter',
      pers_update='2016-05-09'
  WHERE
  Pers_CreateDate &gt;='2016-02-16'
  AND
  Invoice.InvDate &gt; '2016-02-16'
  AND
  Pers_Source = 'Purch';
  </code></pre>
  
  <p>but no luck.  Also have been checking similar questions but I have spent a few days on this question so thank you in advance. </p>