Transform rows to columns(probably pivot) - sql

Question

Here is my requirement:
create table #TEMP
(
KEY_VALUE VARCHAR(100)
,NAME VARCHAR(100)
,AMOUNT INT
,QUANTITY INT
)
INSERT INTO #TEMP
VALUES
('K1','ABC',100,10000),
('K2','XYZ',200,20000),
('K1','ABC',50,5000),
('K2','XYZ',300,30000),
('K3','MNO',50,500)
select * from #TEMP
Because the KEY_VALUE COLUMN matches for 2 rows(K1 and K2), I want to transform it to something as below:
KEY_VALUE NAME AMOUNT_1 AMOUNT_2 QUANTITY_1 QUANTITY_2
K1 ABC 100 50 10000 5000
K2 XYZ 200 300 20000 30000
K3 MNO 50 NULL 500 NULL
What/How do I do that? Please let me know if my question is not clear.

Answer 1

You can use ROW_NUMBER() & do conditional aggregation :
SELECT KEY_VALUE, NAME,
MAX(CASE WHEN seq = 1 THEN AMOUNT END) AS AMOUNT_1,
MAX(CASE WHEN seq = 2 THEN AMOUNT END) AS AMOUNT_2,
MAX(CASE WHEN seq = 1 THEN QUANTITY END) AS QUANTITY_1,
MAX(CASE WHEN seq = 2 THEN QUANTITY END) AS QUANTITY_2
FROM (SELECT t.*,
ROW_NUMBER() OVER (PARTITION BY KEY_VALUE ORDER BY AMOUNT) AS seq
FROM #TEMP t
) t
GROUP BY KEY_VALUE, NAME;
EDIT : If you want to do further calculation then you can use CTE :
WITH CTE AS (
<query>
)
SELECT C.*,
C.AMOUNT_1 - C.AMOUNT_1 AS Diff_Amt
FROM CTE C;

Answer 2

Prepare data
CREATE TABLE #t (
key_value varchar(10),
name varchar(10),
amount int,
quantity int
);
INSERT INTO #t
VALUES
('K1', 'ABC', 100, 10000),
('K2', 'XYZ', 200, 20000),
('K1', 'ABC', 50, 5000),
('K2', 'XYZ', 300, 30000),
('K3', 'MNO', 50, 500);
Querying
WITH t1 (id, key_value, name, amount, quantity)
AS (
SELECT ROW_NUMBER() OVER (ORDER BY key_value), key_value, name, amount, quantity FROM #t
),
t2
AS (
SELECT MIN(id) AS min_id, MAX(id) AS max_id, key_value, name
FROM t1
GROUP BY key_value, name
),
t3
AS (
SELECT t2.key_value, t2.name,
t11.amount AS amount_1, t11.quantity AS quantity_1,
t12.amount AS amount_2, t12.quantity AS quantity_2
FROM t2
INNER JOIN
t1 t11 ON t11.key_value = t2.key_value AND t11.name = t2.name
AND t11.id = t2.min_id
LEFT JOIN
t1 t12 ON t12.key_value = t2.key_value AND t12.name = t2.name
AND t12.id = t2.max_id AND t12.id <> t2.min_id
)
SELECT * FROM t3
Result
key_value name amount_1 quantity_1 amount_2 quantity_2
---------- ---------- ----------- ----------- ----------- -----------
K1 ABC 100 10000 50 5000
K2 XYZ 300 30000 200 20000
K3 MNO 50 500 NULL NULL