title: update with self join results in NULLs
body: <p>I am moving from Access to SQLite. I am trying to recreate this update query:</p>
  
  <h3>Access</h3>
  
  <pre><code>UPDATE FF_WBS_CONSOL
  INNER JOIN FF_WBS_CONSOL AS [FF_WBS_CONSOL_1]
          ON FF_WBS_CONSOL.ParentWBS = [FF_WBS_CONSOL_1].WBS
  SET FF_WBS_CONSOL.WBSLevel = [FF_WBS_CONSOL_1].[WBSLevel]+1 
  </code></pre>
  
  <h3>SQLite</h3>
  
  <pre><code>UPDATE [FF_WBS_CONSOL]
  SET [WBSLevel] = (SELECT P.[WBSLevel]+1
                    FROM [FF_WBS_CONSOL] P
                    WHERE [FF_WBS_CONSOL].[ParentWBS] = P.[WBS])
  </code></pre>
  
  <p>Results are all NULLs.</p>