Bug in "SELECT @sResult = CASE_WHEN LEN(@sResult) = 0 THEN col ELSE @sResult + ',' + col END "

Question

Hello, I want to
report a bug in all versions of SQL
Server
The database I
set collation: SQL_Czech_CP1250_CI_AS
The following script
will return 3:
DECLARE @sResult nvarchar(4000) -- variable to store the resulting string
DECLARE @tab table(col varchar(10) , id int)
--DECLARE @tab table(col nvarchar(10) , id int) -- It works well, but the column in the database is varchar
SET @sResult = ''
insert into @tab(col, id) values ('1',1)
insert into @tab(col, id) values ('2',2)
insert into @tab(col, id ) values ('3',3)
SELECT @sResult = CASE WHEN LEN(@sResult) = 0 THEN col ELSE @sResult + ',' + col END
FROM
@tab
ORDER BY id,col -- works incorrectly
--ORDER BY col -- works incorrectly
--ORDER BY id -- works correctly
SELECT @sResult
When I set
the database Collation: Czech_CI_AS, the script
returns the correct result: 1,2,3.
Stanislav Skalický
pracovník IT
EFG CZ spol. s r.o.
Na Jarově 4, 130 00 Praha
Tel.:     [phone]
Mobil: [phone]
Czech Republic

Answer 1

That is not a good way to concatenate a comma delimited string. There are known issues with the method. 
DECLARE @sResult nvarchar(4000) -- variable to store the resulting string
DECLARE @tab table(col varchar(10) , id int)
SET @sResult = ''
insert into @tab(col, id) values ('1',1)
insert into @tab(col, id) values ('2',2)
insert into @tab(col, id ) values ('3',3)
SELECT @sResult = CASE WHEN LEN(@sResult) = 0 THEN col ELSE @sResult + ',' + col END
FROM
@tab
-- ORDER BY id,col -- 1,2,3
-- ORDER BY col -- 1,2,3
-- ORDER BY id -- 1,2,3
-- ORDER BY col COLLATE SQL_Czech_CP1250_CI_AS -- 3
-- ORDER BY id, col COLLATE SQL_Czech_CP1250_CI_AS -- 3
-- ORDER BY col COLLATE Czech_CI_AS -- 3
-- ORDER BY newid() -- 3
-- no ORDER BY 1,2,3
SELECT @sResult
Use the XML PATH method instead:
http://www.sqlusa.com/bestpractices/training/scripts/commadelimitedlist/
Kalman Toth Database & OLAP Architect
SQL Server 2014 Database Design
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