SQL Server processing for jquery datatables order by issue? - sql

Question

I have written the following script to mimic the incoming parameters from datatables and try to filter the results using the parameters. Everything works fine except the order by clause. Basically it only orders by rownumber and does not take into consideration the case statement which provides the second order by column.
declare #sSortColumn as nvarchar(50)='Country';
declare #sSortDirection as nvarchar(5) = 'Desc';
declare #sSearch as nvarchar(50) = '';
declare #iDisplayLength as int = 20;
declare #iDisplayStart as int = 20;
declare #sIDsearch as int = CASE WHEN ISNUMERIC(#sSearch) = 1 THEN CAST(#sSearch AS INT) ELSE 0 END;
WITH media AS
(
select ROW_NUMBER() OVER (ORDER BY mc.id) as RowNumber,
mc.id,mc.Name, mc.CityID,lc.Name as Country
from Lookup_MediaChannels mc
left join Lookup_SonarMediaTypes st on mc.SonarMediaTypeID = st.ID
left join Lookup_SonarMediaGroups sg on sg.ID = st.SonarMediaGroupID
left join Lookup_MediaTypes mt on mc.MediaTypeID = mt.ID
left join Lookup_SonarMediaGroups sg1 on sg1.ID = mt.MediaGroupID
left join lookup_Countries lc on lc.id = mc.countryid
where mc.Name like '%'+#sSearch+'%'
and (sg1.ID=1 or sg.ID =1 )
or mc.id = #sIDsearch
)
SELECT RowNumber, Name, Country
FROM media
WHERE RowNumber BETWEEN (#iDisplayStart+ 1) AND (#iDisplayStart+ #iDisplayLength)
order by rownumber,
CASE WHEN #sSortColumn = 'Name' AND #sSortDirection = 'Desc'
THEN Name END DESC,
CASE WHEN #sSortColumn = 'Name' AND #sSortDirection != 'Desc'
THEN Name END,
CASE WHEN #sSortColumn = 'Country' AND #sSortDirection = 'Desc'
THEN Country END DESC,
CASE WHEN #sSortColumn = 'Country' AND #sSortDirection != 'Desc'
THEN Country END

Answer 1

This simplified example may help you
http://sqlfiddle.com/#!6/35ffb/10
Set up some dummy data (this would be replaced by your select statement)
create table x(
id int,
name varchar(3),
country varchar(2)
)
insert into x
values (1,'aaa','uk'),
(2,'aaa','us'),
(3,'baa','uk'),
(4,'caa','uk'),
(5,'baa','it')
Some vars to hold sort field and sort order
declare #so char(1)
declare #sf char(1)
set #so = 'a' -- a = asc d = desc
set #sf = 'n' -- n = name c = country
and a select to return sorted data
SELECT row_number()
OVER (order by
CASE WHEN #so = 'd' THEN sf END desc,
CASE WHEN #so <> 'd' THEN sf end,
id
) AS aa, name,country
FROM (
SELECT x.*, case #sf when 'n' then name when 'c' then country end sf
FROM X
) X