TSQL USE ROW_NUMBER IN CTE, SELECT ORDER BY NOT WORKING - sql-server

Question

I preapare string from row of nubmers. When I use the row_number function, the order by clause not working
DECLARE #text VARCHAR(MAX)
IF OBJECT_ID('tempdb..#numbers') IS NOT NULL DROP TABLE #numbers
SELECT CAST(ROW_NUMBER() OVER (ORDER BY name) AS INT) AS number INTO #numbers FROM master..spt_values
SET #text = ''
;WITH
numbers (number)
AS
(
SELECT CAST(ROW_NUMBER() OVER (ORDER BY name) AS INT) AS number FROM master..spt_values
),
a
AS
(
SELECT number FROM numbers WHERE number < 10
),
b
AS
(
SELECT number FROM numbers WHERE number < 10
)
SELECT #text = #text + LTRIM(STR(a.number*b.number))
FROM a
CROSS JOIN b
ORDER BY a.number, b.number DESC
SELECT #text
result "9"
SET #text = ''
;WITH
numbers (number)
AS
(
SELECT number FROM #numbers
),
a
AS
(
SELECT number FROM numbers WHERE number < 10
),
b
AS
(
SELECT number FROM numbers WHERE number < 10
)
SELECT #text = #text + LTRIM(STR(a.number*b.number))
FROM a
CROSS JOIN b
ORDER BY a.number, b.number DESC
SELECT #text
result "9876543211816141210864227242118151296336322824201612844540353025201510554484236302418126635649423528211477264564840322416881726354453627189"
Where is diference ?

Answer 1

I expect this is related to this issue, in summary when you use variable concatenation, e.g.
SELECT #Variable = #Variable + someField
FROM Table
ORDER BY AnotherField;
The results are dependant on physical implementation and internal access paths. I am currently struggling to find benchmark tests on the internet, but I think the fastest, reliable approach in SQL Server is to use XML extensions to concatenate rows to columns:
WITH Numbers AS (SELECT * FROM (VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9)) t (Number))
SELECT [Text] = (SELECT LTRIM(STR(a.number*b.number))
FROM Numbers AS A
CROSS JOIN Numbers AS B
ORDER BY A.Number, b.Number DESC
FOR XML PATH(''), TYPE).value('.', 'VARCHAR(MAX)');
N.B. I have also removed the reference to master..spt_values and replaced with a table value constructor - this just adds unnecessary reads to generate a sequence from 1 to 9.
If you need more numbers for your sequence I would still not use system tables, use Iztik Ben-Gan's stacked CTE approach, as described in this article:
DECLARE #Numbers INT = 100000;
WITH N1 AS (SELECT N FROM (VALUES (1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) t (N)),
N2 (N) AS (SELECT 1 FROM N1 AS N1 CROSS JOIN N1 AS N2),
N3 (N) AS (SELECT 1 FROM N2 AS N1 CROSS JOIN N2 AS N2),
N4 (N) AS (SELECT 1 FROM N3 AS N1 CROSS JOIN N3 AS N2),
Numbers (Number) AS (SELECT TOP (#Numbers) ROW_NUMBER() OVER(ORDER BY N) FROM N4)
SELECT Number
FROM Numbers;

Answer 2

Do not use cast on ROW_NUMBER(). This will return same as your second query:
DECLARE #text VARCHAR(MAX) = ''
;WITH
numbers (number)
AS
(
SELECT ROW_NUMBER() OVER (ORDER BY name) AS number FROM master..spt_values
),
a
AS
(
SELECT number FROM numbers WHERE number < 10
),
b
AS
(
SELECT number FROM numbers WHERE number < 10
)
SELECT #text = #text + LTRIM(STR(a.number*b.number))
FROM a
CROSS JOIN b
ORDER BY a.number, b.number DESC
Also don't define twice the same in CTE use aliases instead:
DECLARE #text VARCHAR(MAX) = ''
;WITH
numbers (number)
AS
(
SELECT ROW_NUMBER() OVER (ORDER BY name) AS number FROM master..spt_values
),
a
AS
(
SELECT number FROM numbers WHERE number < 10
)
SELECT #text = #text + LTRIM(STR(a.number*b.number))
FROM a AS a
CROSS JOIN a AS b
ORDER BY a.number, b.number DESC
SELECT #text