Question

I have a requirement to order a result set by a column, based on an Integer input into a parameter.

Problem is, I need to use a CASE for the OrderBy, and it seems the code accepts the first ‘TYPE’ in the case column… any other types fail.

My code is like this:

    WITH error_table AS  
 (  
  SELECT Row_Number() OVER   
   (ORDER BY  
        CASE @orderBy
            WHEN 1 THEN received_date  -- Last Rx'd message  
            WHEN 2 THEN message_id -- Message Id  
            WHEN 3 THEN zibmat.short_name -- Message action type  
            WHEN 4 THEN error_action.short_name -- Status type  
            WHEN 5 THEN ime.[allocated_date] -- Allocated Date  
            ELSE received_date
    END) AS RowNumber   

   ,ime.[ijis_message_error_id]  
      ,ime.[message_id]  
      ,ime.[message_version] 

So, when OrderBy is 1, it works. It sorts by rx_date… but when I sent it a 2, it fails with a data time conversion error.

It looks like all the types must be the same…

Sending a 5 works fine, as that’s a date time too.

Is there a way I can fix this?

Answer 1

A CASE statement must resolve to only one data type. This is regardless of the fact that you know that @orderby will choose only one branch and it will be a particular data type.

You could use something like this, which would be clunky but will work.

ORDER BY
CASE @orderBy WHEN 1 THEN received_date -- Last Rx'd message
WHEN 2 THEN 0
WHEN 3 THEN 0
WHEN 4 THEN 0
WHEN 5 THEN ime.[allocated_date] -- Allocated Date
ELSE received_date END,
CASE @orderBy WHEN 1 THEN 0
WHEN 2 THEN message_id -- Message Id
WHEN 3 THEN 0
WHEN 4 THEN 0
WHEN 5 THEN 0
ELSE 0 END,
CASE @orderBy WHEN 1 THEN ''
WHEN 2 THEN ''
WHEN 3 THEN zibmat.short_name -- Message action type
WHEN 4 THEN error_action.short_name -- Status type
WHEN 5 THEN ''
ELSE '' END