title: TableA Left Join (a subset of) Table B
body: <p>I want to left join TableA to TableB where a certain condition in tableA is true
  So I do this type of SQL query</p>
  
  <pre><code>Select * from
  TableA Left Join TableB on TableA.fld1 = TableB.fld2
  where TableA.fld3 = True
  </code></pre>
  
  <p>This works OK.
  Now however I want to do the Join only with certain records in TableB, ie those records
  in TableB where a certain condition is met, specifically <em>fld4</em> has <strong>false</strong> as its value. The reason I want to do this is I want to know which rows in tableA don't have a match in tableB among the rows in tableB where <em>fld4</em> is <strong>false</strong>.</p>
  
  <p>If I was to delete all the rows in TableB where <em>fld4</em> is <strong>true</strong> and run the above query
  I'd get the correct result. All I'd need to do is find the rows in the resultant recordset  with null in some cell.
  But if instead of deleting rows from TableB first I alter the query to the one below I get no rows at all returned</p>
  
  <pre><code>Select * from
  TableA Left Join TableB on TableA.fld1 = TableB.fld2
  where TableA.fld3 = True
  and TableB.fld4 = false
  </code></pre>
  
  <p>If my ramblings make sense can someone tell me what I'm doing wrong?
  Thanks</p>