title: Handling non existent values in sql query expression for ssrs chart
body: <p>I am using the following query in an ssrs line chart. It counts how many orders are recorded each month based on each order date.</p>
  
  <p>My problem is that when a month has no orders, rather than saying zero or null it removes the row for that month all together. I would prefer for it to count it as zero but null would be ok too.</p>
  
  <p>Basically, I want to always have twelve rows whether they contain information or not.</p>
  
  <p>How can I fix this? Is there an expression I can use or something? Or am I missing something completely obvious?</p>
  
  <pre><code>SELECT
  MONTH(Ord.OrdDate) AS 'MONTH',
  COUNT(CASE WHEN @Worker_ID1 IS NULL OR @Worker_ID1 = Worker.ID THEN 1 END) AS 'Worker1',
  COUNT(CASE WHEN @Worker_ID2 IS NULL OR @Worker_ID2 = Worker.ID THEN 1 END) AS 'Worker2',
  COUNT(CASE WHEN @Worker_ID3 IS NULL OR @Worker_ID3 = Worker.ID THEN 1 END) AS 'Worker3',
  COUNT(CASE WHEN @Worker_ID4 IS NULL OR @Worker_ID4 = Worker.ID THEN 1 END) AS 'Worker4',
  COUNT(CASE WHEN @Worker_ID5 IS NULL OR @Worker_ID5 = Worker.ID THEN 1 END) AS 'Worker5'
  
  FROM Ord
  JOIN Prod ON Ord.Prod_ID = Prod.ID
  JOIN ProdType ON Prod.ProdType_ID = ProdType.ID
  JOIN Grouping ON Ord.Grouping_ID = Grouping.ID
  JOIN Worker ON Grouping.Worker_ID = Worker.ID
  
  WHERE @Year = YEAR(Ord.OrdDate)
  AND (@ProdType_ID IS NULL OR @ProdType_ID = ProdType.ID)
  
  GROUP BY MONTH(Ord.OrdDate)
  </code></pre>