Reference an alias elsewhere in the SELECT list

Question

I have the following query:

    select FirstName, LastName,
    Case
     When LastName = \'Jones\'
     then \'N/A\'
    End as Other,
    Case 
      When          


        

Answer 1

You can't refer to an alias outside of SELECT and ORDER BY because of the way a query is parsed. Typical workaround is to bury it in a derived table:

SELECT 
  FirstName, LastName, Other, 
  Flag = CASE WHEN Other IS NOT NULL THEN 1 ELSE 0 END
FROM 
(
  SELECT FirstName, LastName,
    CASE WHEN LastName = 'Jones'
     THEN 'N/A'
    END AS Other
  FROM dbo.table_name
) AS x;