title: Returning null instead of empty rows for a particular column in an SQL query
body: <p>We have a Table which is really a 2D array where each (Row, Column) represents a particular piece of data, for example (1,4) might represent the Location and (2,4) might represent the Price of pizza.</p>
  
  <p>For a particular Person, they will have exactly one entry for each (Row, Column).
  Sometimes this data might need translation, for example Location might be stored as L for London and M for Manchester. We then have a separate table called Location mapping which translate L to London and M to Manchester.
  Sometimes we don't need any translation, for example the price can just be returned as-is.</p>
  
  <p>In effect, what I am hoping to do is to find some SQL to convert this 2D Array into a 1-row output:</p>
  
  <p>Original Table:</p>
  
  <pre><code> RowNo | C1 | C2
   ------+----+-----
   R1    | L  | 2.0
   R2    | 50 | J
  </code></pre>
  
  <p>So:</p>
  
  <pre><code>(1,1) represent location,
  (1,2) represents price of pizza
  (2,1) represnts age
  (2,2) represents Initials
  </code></pre>
  
  <p>Only location needs to be translated.</p>
  
  <p>What I would like is to get back:</p>
  
  <pre><code> Location | PriceOfPizza | Age | Initials
   ---------+--------------+-----+---------
   London   |     2.0      | 50  |    J
  </code></pre>
  
  <p>Now if L does not exist in the LocationTranslation table, I still want to return the row but with just a blank value (or null) under the Location column.</p>
  
  <p>Please could anyone help?</p>
  
  <p>Thanks,
  Wing</p>