SQL Case with 2 conditions [duplicate] - sql

Question

This question already has answers here:
T-SQL Conditional Order By
(4 answers)
Closed 8 years ago.
I have a stored procedure that will accept 2 different parameters. The first parameter will determine which column I want to sort on, the second parameter will determine whether it is ASC or DESC
Create Procedure Some_SP
#sortcolumn varchar(10)
#sortorder varchar(10)
AS
Select * from empTable
Order by
CASE #sortcolumn WHEN 'First_Name' THEN fname END,
CASE #sortcolumn WHEN 'Last_Name' THEN lname END,
CASE #sortcolumn WHEN 'ID' THEN empID END,
CASE #sortorder WHEN 'ascending' THEN ASC END,
CASE #sortorder WHEN 'descending' THEN DESC END
It is giving me syntax error. How do I fix it so that I can have 2 conditions in my CASE statement?

Answer 1

The following will work:
Select * from empTable
Order by
CASE WHEN #sortcolumn = 'First_Name' AND #SortOrder = 'ascending' THEN fname END ASC,
CASE WHEN #sortcolumn = 'First_Name' AND #SortOrder = 'descending' THEN fname END DESC
etc...
In order to avoid typing each of these case statements by hand, you could write a "generator" script that you use to create this (especially good if the table definition would change):
SELECT
'CASE WHEN #SortColumn = ''' + C.name + ''' AND #SortOrder = ''ascending'' THEN ' + C.name + ' END ASC,' + CHAR(13) + CHAR(10) +
'CASE WHEN #SortColumn = ''' + C.name + ''' AND #SortOrder = ''descending'' THEN ' + C.name + ' END DESC,'
FROM sys.columns C
WHERE C.object_id = object_id('[Schema].[Table]')

Answer 2

If you want to avoid dynamic SQL and using 2x your conditions, you can use row_number
eg:
declare #t table (string varchar(50), number int)
insert #t values ('a',9),('f',2),('c',1)
declare
#sc varchar(10) = 'number', -- or 'string', etc
#so varchar(10) = 'desc' -- or 'asc'
select *
from
(
select
*,
case #sc when 'string' then ROW_NUMBER() over (order by string)
when 'number' then ROW_NUMBER() over (order by number)
end rn
from #t
) v
order by
case #so when 'desc' then -rn else rn end

Answer 3

You can just copy and paste and run this. I hate dynamic SQL, don't do it.
Unfortunately you'll have to duplicate the query....but it solves your specific problem.
DECLARE
#sortcolumn varchar(10),
#sortorder varchar(10)
SET #sortcolumn = 'fname'
SET #sortorder = 'DESC'
DECLARE
#Data TABLE
(
fname nvarchar(10),
lname nvarchar(10),
empID int
)
INSERT INTO #Data VALUES ('BBB', 'BBB', 2)
INSERT INTO #Data VALUES ('AAA', 'AAA', 1)
IF #sortorder = 'DESC' BEGIN
SELECT
*
FROM
#Data
ORDER BY
CASE
WHEN #sortcolumn = 'fname' THEN fname
WHEN #sortcolumn = 'lname' THEN lname
END
DESC
END ELSE BEGIN
SELECT
*
FROM
#Data
ORDER BY
CASE
WHEN #sortcolumn = 'fname' THEN fname
WHEN #sortcolumn = 'lname' THEN lname
END
END

Answer 4

Modifying Jon's answer to cap the ORDER BY list at just 2 instead of 2 * #columns
SELECT *
FROM MyTable
CROSS APPLY (VALUES
('First_Name',fname),
('Last_Name' ,lname),
('Id' ,ID )
) sort(SortColumn, SortValue)
WHERE SortColumn = #SortColumn
ORDER BY
CASE #SortOrder WHEN 'ascending' THEN SortValue END ASC,
CASE #SortOrder WHEN 'descending' THEN SortValue END DESC