title: If subquery returns no rows, return 0 else return value of the subquery
body: <p>I got a question and you can most likely help me.
  I have got a query with a subquery that narrows the search. The query ends with this.</p>
  
  <pre><code>SELECT 
      * 
  FROM 
      Purchase
  WHERE
      Total &lt; 5000
  AND 
      Total &gt; 
              (
                  SELECT TOP 1
                     buyamount
                  FROM
                     employee
                  WHERE
                     manager = 'TST'
                  ORDER BY
                     buyamount ASC
              )
  ORDER BY Date DESC
  </code></pre>
  
  <p>I want the value of the subquery after the ">"... but if the subquery gives nothing in return, i want it to be 0. How do i do this?</p>