order by using terms in where clause - sql

Question

I have a simple select query -
SELECT ID, NAME
FROM PERSONS
WHERE NAME IN ('BBB', 'AAA', 'ZZZ')
-- ORDER BY ???
I want this result to be ordered by the sequence in which NAMES are provided, that is,
1st row in result set should be the one with NAME = BBB, 2nd is AAA, 3rd it ZZZ.
Is this possible in SQL server ? I would like to know how to do it if there is a simple and short way of doing it, like maybe 5-6 lines of code.

Answer 1

You could create an ordered split function:
CREATE FUNCTION [dbo].[SplitStrings_Ordered]
(
#List NVARCHAR(MAX),
#Delimiter NVARCHAR(255)
)
RETURNS TABLE
AS
RETURN (SELECT [Index] = ROW_NUMBER() OVER (ORDER BY Number), Item
FROM (SELECT Number, Item = SUBSTRING(#List, Number,
CHARINDEX(#Delimiter, #List + #Delimiter, Number) - Number)
FROM (SELECT ROW_NUMBER() OVER (ORDER BY s1.[object_id])
FROM sys.all_objects AS s1 CROSS JOIN sys.all_objects AS s2) AS n(Number)
WHERE Number <= CONVERT(INT, LEN(#List))
AND SUBSTRING(#Delimiter + #List, Number, LEN(#Delimiter)) = #Delimiter
) AS y);
Then alter your input slightly (a single comma-separated list instead of three individual strings):
SELECT p.ID, p.NAME
FROM dbo.PERSONS AS p
INNER JOIN dbo.SplitStrings_Ordered('BBB,AAA,ZZZ', ',') AS s
ON p.NAME = s.Item
ORDER BY s.[Index];

Answer 2

You could store the names in a temp table with an order. Example:
DECLARE #Names TABLE (
Name VARCHAR(MAX),
SortOrder INT
)
INSERT INTO #Names (Name, SortOrder) VALUES ('BBB', 1)
INSERT INTO #Names (Name, SortOrder) VALUES ('AAA', 2)
INSERT INTO #Names (Name, SortOrder) VALUES ('ZZZ', 3)
SELECT P.ID, P.NAME
FROM PERSONS P
JOIN #Names N ON P.Name = N.Name
ORDER BY N.SortOrder

Answer 3

There is no way to do this using the order in the IN predicate, however, you could create a table of constants giving your constants an order by value:
SELECT p.ID, p.NAME
FROM PERSONS p
INNER JOIN
( VALUES
('BBB', 1),
('AAA', 2),
('ZZZ', 3)
) t (Name, SortOrder)
ON p.Name = t.Name
ORDER BY t.SortOrder;
The other (and in my option less attractive) solution is to use CASE
SELECT ID, NAME
FROM PERSONS
WHERE NAME IN ('BBB', 'AAA', 'ZZZ')
ORDER BY CASE Name
WHEN 'BBB' THEN 1
WHEN 'AAA' THEN 2
WHEN 'ZZZ' THEN 3
END;

Answer 4

SELECT ID, NAME
FROM PERSONS
WHERE NAME IN ('BBB', 'AAA', 'ZZZ')
ORDER BY CASE
WHEN NAME = 'BBB' THEN 1
WHEN NAME = 'AAA' THEN 2
WHEN NAME = 'ZZZ' THEN 3
END ASC

Answer 5

I think this must work:
ORDER BY CASE
WHEN NAME = 'BBB' THEN 0
WHEN NAME = 'AAA' THEN 1
WHEN NAME = 'ZZZ' THEN 2
ELSE 3
END ASC