I am trying to use this article's advice, but am getting wierd results. When I sort by any field which is date or numeric (proj_id or request_received) it works fine - when I try to sort by any char field (such as proj_name) I get the following error...

Server: Msg 241, Level 16, State 1, Line 7

Syntax error converting datetime from character string.

I don't understand this at all - I can remove the case statement and substitute proj_name in the order by clause and it works fine.

declare @proj_id_inint,

   @order_by_inchar(30)



set @proj_id_in = NULL

set @order_by_in = 'proj_lead'



SELECT a.proj_id, a.proj_name, a.proj_desc, a.proj_priority, convert(char(10),a.request_received,101) as 'request_received', convert(char(10),a.due_date,101) as 'due_date', 

   convert(char(10),a.date_completed,101) as 'date_completed',

   b.team_desc, c.emp_lname + ', ' + c.emp_fname as 'proj_lead', a.client_contact, d.status_desc

from cts_proj a

   JOIN cts_team b on a.team_code = b.team_code

   JOIN cts_emp c on a.proj_lead = c.emp_id

   JOIN cts_status d on a.status_code = d.status_code

WHERE (@proj_id_in IS NULL OR a.proj_id = @proj_id_in)

order by 

 CASE rtrim(@order_by_in)

WHEN 'proj_id' THEN a.proj_id

WHEN 'proj_name' THEN a.proj_name

WHEN 'proj_priority' THEN a.proj_priority

WHEN 'requested_date' THEN a.request_received

WHEN 'due_date' THEN a.due_date

WHEN 'completion_date' THEN a.date_completed

WHEN 'proj_lead' THEN a.proj_name

WHEN 'client_contact' THEN client_contact

WHEN 'status_desc' THEN status_desc

 END