Concatanating Pairs of Rows SQL Server [duplicate] - sql-server

Question

This question already has answers here:
Concatenate row values T-SQL
(15 answers)
Closed 7 years ago.
I have the following table, sorted.
ID Value Amount
1 A 10.00
2 B 4.25
3 C 2.01
4 D 5.00
How can I concatenate only consecutive pairs of rows and turn it to this:
ID Col1 Col2
1,2 A,B 10.00,4.25
3,4 C,D 2.01,5.00
And I don't want to use user-defined tables or temp tables. I am open to using
the window functions provided in SQL Server 2012 and 2014 though.

Answer 1

I looked at the other solutions and thought it was overkill, so I reused some and excluded or rewrote the unnecessary parts. This should result in better performance.
;WITH cte (rn, id, Value, Amount)
AS
(
SELECT ROW_NUMBER() OVER(ORDER BY id), id, Value, Amount
FROM yourtable
)
SELECT
( SELECT CAST(T.id AS VARCHAR(10)) + ','+ CAST(T1.id AS VARCHAR(10))
FROM cte AS T1
WHERE T1.rn = T.rn + 1) ID,
( SELECT CAST(T.value AS VARCHAR(10)) + ','+ CAST(T1.value AS VARCHAR(10))
FROM cte AS T1
WHERE T1.rn = T.rn + 1) COL1,
( SELECT CAST(T.Amount AS VARCHAR(10)) + ','+ CAST(T1.Amount AS VARCHAR(10))
FROM cte AS T1
WHERE T1.rn = T.rn + 1) COL2
FROM cte AS T
WHERE rn % 2 = 1

Answer 2

Try this,if it do not work with other sample data then let me know,
Declare #t table(ID varchar(50), Value varchar(50), Amount float)
insert into #t values(1,'A',10.00),(2,'B', 4.25),(3,'C',2.01)
,(4,'D',5.00 )
--Get the maxid
declare #MaxID int=(Select max(id) from #t)
;WITh CTE AS
(
SELECT ID,
STUFF((select ','+ id from #t where id IN(1,2) for xml path('')),1,1,'') [id1]
,STUFF((select ','+ Value from #t where id IN(1,2) for xml path('')),1,1,'') [Value]
,STUFF((select ','+ cast(Amount as varchar) from #t where id IN(1,2) for xml path('')),1,1,'') [Amount]
,1 RN
FROM #T a WHERE ID=1
UNION ALL
SELECT B.ID,
STUFF((select ','+ id from #t where id IN(RN+2,RN+3) for xml path('')),1,1,'')
,STUFF((select ','+ Value from #t where id IN(RN+2,RN+3) for xml path('')),1,1,'')
,STUFF((select ','+ cast(Amount as varchar) from #t where id IN(RN+2,RN+3) for xml path('')),1,1,'')
, RN+2
FROM cte a
CROSS APPLY(SELECT * FROM #T WHERE ID=RN+2 AND ID<=#MaxID) B
)
SELECT ID1,Value,Amount FROM CTE

Answer 3

This works just fine.. We just generate unique IDs for each pair using row_number and concatenate using FOR XML PATH on these IDs:
DECLARE #Test TABLE
(
ID VARCHAR(50)
, Value VARCHAR(50)
, Amount FLOAT
);
INSERT INTO #Test
(ID, Value, Amount)
VALUES
(1, 'A', 10.00)
, (2, 'B', 4.25)
, (3, 'C', 2.01)
, (4, 'D', 5.00);
;WITH cte (rn, id, Value, Amount)
AS
(
SELECT (ROW_NUMBER() OVER(ORDER BY id) + 1) / 2, id, Value, Amount
FROM #Test
)
SELECT DISTINCT
STUFF((SELECT ',' + CAST(T1.id AS VARCHAR(10))
FROM cte AS T1
WHERE T1.rn = T.rn
ORDER BY T1.id
FOR XML PATH('')), 1, 1, '') AS ID
, STUFF((SELECT ',' + CAST(T2.Value AS VARCHAR(10))
FROM cte AS T2
WHERE T2.rn = T.rn
ORDER BY T2.id
FOR XML PATH('')), 1, 1, '') AS Col1
, STUFF((SELECT ',' + CAST(T3.Amount AS VARCHAR(10))
FROM cte AS T3
WHERE T3.rn = T.rn
ORDER BY T3.id
FOR XML PATH('')), 1, 1, '') AS Col2
FROM cte AS T
Output:
ID Col1 Col2
-------------------
1,2 A,B 10,4.25
3,4 C,D 2.01,5