title: select same columns twice in MS SQL
body: <p>Have a select Statement like</p>
  
  <pre><code>select 
  SouceField_A  
  + 'DeliminiterCharacter'
  + SouceField_A
  + 'DeliminiterCharacter'
  + SourceField_B
  + 'DeliminiterCharacter'
  ...
  </code></pre>
  
  <p>Problem is that in real life I do not have a simple Field, but have CASE WHEN ... END. This makes it error prone and difficult to Keep both places up to date when Change is required.
  For this I wonder if there is an easy way to put it into variable etc.</p>
  
  <p>Below is part of query to Show </p>
  
  <pre><code>select 
  ISNULL ( Oracle_Update , 'create' )  + '~' +
  @Email + '~' +
  @ItemNo + '~' +
  ''  + '~' +
  'D'  + '~' +
  ISNULL ( Item_Desc_DE , '' )  + '~' +
  REPLACE(REPLACE(ISNULL ( Item_Specification_DE , '' ), CHAR(13), ''), CHAR   (10), ' $#') + '~' +    
  ISNULL ( Item_Copy_From, '' ) + '~' +
   -- master template
   CASE WHEN Oracle_Update like 'update' OR item_copy_from is not NULL
  THEN 
      ''
      ELSE  ISNULL ( Item_Template , 'MAG Assembly' )
  END         + '~' +
  CASE WHEN Oracle_Update like 'update' OR item_copy_from is not NULL 
  THEN 
      ''
      ELSE  ISNULL 
  </code></pre>