How to make conditional ordering for two or more columns
-
16-10-2019 - |
Question
In MS SQL Server 2005 I am writing one query with conditional sort and my problem is that I do not know how can I sort conditional using two columns?
If I wrote code like this it is working normaly
select
*
from
table
order by
case @pkr
when 'kol' then kol
when 'nci' then nci
end
I do not know how to make conditional ordering for two or more columns
select
*
from
table
order by
case @pkr
when 'KOL-NCI' then kol,nci
when 'kol-MPCI' then kol,mpci
end
There is an idea to make dynamic TSQL and use sp_executesql
but I am still looking for a better idea?
Solution
I'll admit I've never had to do this before so there was a bit of head scratching involved. Simple example table to demonstrate:
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[MyTable]') AND type in (N'U'))
DROP TABLE [dbo].[MyTable]
GO
CREATE TABLE dbo.MyTable
(
col1 INT
, col2 CHAR(1)
)
GO
INSERT dbo.MyTable (col1, col2) VALUES (1, 'A')
INSERT dbo.MyTable (col1, col2) VALUES (1, 'B')
INSERT dbo.MyTable (col1, col2) VALUES (1, 'C')
INSERT dbo.MyTable (col1, col2) VALUES (2, 'A')
INSERT dbo.MyTable (col1, col2) VALUES (2, 'B')
INSERT dbo.MyTable (col1, col2) VALUES (2, 'C')
INSERT dbo.MyTable (col1, col2) VALUES (3, 'A')
INSERT dbo.MyTable (col1, col2) VALUES (3, 'B')
INSERT dbo.MyTable (col1, col2) VALUES (3, 'C')
Using an @SortStyle parameter to differentiate between sort orders, @SortStyle =1 will sort by col1 ASC, col2 DESC
and @SortStyle=2 sort by col2 DESC, col1 ASC
.
DECLARE @SortStyle INT
SET @SortStyle = 1
SELECT
col1
, col2
FROM
dbo.MyTable
ORDER BY
CASE
WHEN @SortStyle = 1 THEN col1
END ASC,
CASE
WHEN @SortStyle = 1 THEN col2
END DESC,
CASE
WHEN @SortStyle = 2 THEN col2
END DESC,
CASE
WHEN @SortStyle = 2 THEN col1
END ASC
SET @SortStyle = 2
SELECT
col1
, col2
FROM
dbo.MyTable
ORDER BY
CASE
WHEN @SortStyle = 1 THEN col1
END ASC,
CASE
WHEN @SortStyle = 1 THEN col2
END DESC,
CASE
WHEN @SortStyle = 2 THEN col2
END DESC,
CASE
WHEN @SortStyle = 2 THEN col1
END ASC
How do you ORDER BY a parameter covers the simpler case of sorting by just 1 column.
OTHER TIPS
Assuming you have more cases (I added one), and all types are compatible,
order by
case @pkr
when 'KOL-NCI' then kol
when 'kol-MPCI' then kol
when 'foo-bar' then foo
end,
case @pkr
when 'KOL-NCI' then nci
when 'kol-MPCI' then mpci
when 'foo-bar' then bar
end
It isn't a multi-column sort: you have a primary sort, followed by a secondary sort. Just look at the sort dialogue box in Excel to see what I mean.
With the example you give it is simple:
select *
from table
order by kol, case @pkr
when 'KOL-NCI' then nci
when 'kol-MPCI' then mpci
end
There is an idea to make dynamic TSQL and use
sp_executesql
but I am still loking for better idea.
It is always nice to avoid dynamic SQL where possible