title: Find nearby postcode with a base postcode
body: <p>This is with reference to this question: <a href="https://stackoverflow.com/questions/5624210/find-uk-postcodes-closest-to-other-uk-post-codes-by-matching-the-post-code-string">Find UK PostCodes closest to other UK Post Codes by matching the Post Code String</a></p>
  
  <pre><code>--User wants to get all postcodes nearby B193SH
  -- Postcode  = 'B193SH'
  -- Latitude  = 52.488460
  -- Longitude = -1.895690
  
  SELECT [HouseNumber],
               [Street],
               [Area],
               [PostCode],
               [Latitude],
               [Longitude],
  FROM   [dbo].[Address]
  WHERE  ([Latitude]  BETWEEN ( 52.488460 - 0.100000 ) AND ( 52.488460 + 0.100000 )) AND 
               ([Longitude] BETWEEN ( -1.895690 - 0.100000 ) AND ( -1.895690 + 0.100000 ))
  ORDER  BY [PostCode]
  GO 
  </code></pre>
  
  <p>Executing this query, i get a couple of results. But the question stands that what difference (meters/miles) does a +/- 0.100000 to Lat/Lon makes?</p>
  
  <p>Should I try to find close postcodes by using the first three letter of the base postcode, i.e., 'B19'?</p>
  
  <p>Please see the reference question for a full detail of my scenerio.</p>
  
  <p>Thanks!</p>