title: Check if a SQL Select statement returns no rows
body: <p>I have a select statement </p>
  
  <pre><code>SELECT     QBalance
  FROM         dbo.CustomerBalance
  WHERE     (CustomerID = 1) AND (MarchentID = @MerchantId)
  </code></pre>
  
  <p>I want to check if that statement returns 0 rows. I tried to use the ISNULL and IFNULL but it seems that I'm missing something.</p>