Oracle dynamic DESC and ASC in order by

Question

Order by is dynamic but the sort order is static.

SELECT ...
Order By CASE WHEN InputParam = 'PRICE' THEN OFFER_PRICE END DESC,
         CASE WHEN InputParam = 'ENDING SOON' THEN EXPIRY_DATE END DESC, 
         CASE WHEN InputParam = 'DISCOUNT' THEN DISC_PERCENTAGE END DESC,
         CASE WHEN InputParam = 'SAVING' THEN SAVING END DESC

Now I need to make sure that the sort order is also dynamic. Is there some way to make sort order dynamic in the above query?

Answer 1

If you also want to make the sort order (ASC/DESC) dynamic, you could do the following:

SELECT ...
Order By CASE WHEN InputParam = 'PRICE' THEN l_so * OFFER_PRICE END,
         CASE WHEN InputParam = 'ENDING SOON' 
              THEN l_so * (SYSDATE - EXPIRY_DATE) END, 
         CASE WHEN InputParam = 'DISCOUNT' THEN l_so * DISC_PERCENTAGE END,
         CASE WHEN InputParam = 'SAVING' THEN l_so * SAVING END

with a variable l_so that contains 1 or -1 depending upon which sort order you want.

Answer 2

This works for me:

order by 
  case when :dir_param = 'ASC' then
    case :col_param 
      when 'col_1_identifier' then col_1_name
      when 'col_2_identifier' then col_2_name
      ...
    end
  end,
  case when :dir_param = 'DSC' then
    case :col_param 
      when 'col_1_identifier' then col_1_name
      when 'col_2_identifier' then col_2_name
      ...
    end
  end desc

or

order by 
case when :dir_param = 'ASC' and :col_param = 'col_1_identifier' then col_1_name end,
case when :dir_param = 'DSC' and :col_param = 'col_1_identifier' then col_1_name end desc,
case when :dir_param = 'ASC' and :col_param = 'col_2_identifier' then col_2_name end,
case when :dir_param = 'DSC' and :col_param = 'col_2_identifier' then col_2_name end desc

replace literals, variable and column names with those specific to your situation. Oracle seemed to be very picky about the placement of the desc sort direction qualifier.