Grouping_sets getting different output formats when group by changed - oracle

Question

I have the following test CASE which is working fine.
When I try to group by customer_id, TO_CHAR (p.purchase_date, 'IYYY"W"IW') I'm not getting the same format as the working query. As a workaround I could limit the query to 1 customer_id each time with a where clause but I really don't want to do that.
Can someone please tell me what the problem is and how to rectify the issue.
ALTER SESSION SET NLS_TIMESTAMP_FORMAT = 'DD-MON-YYYY HH24:MI:SS.FF';
ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';
CREATE TABLE customers
(CUSTOMER_ID, FIRST_NAME, LAST_NAME) AS
SELECT 1, 'Faith', 'Mazzarone' FROM DUAL UNION ALL
SELECT 2, 'Lisa', 'Saladino' FROM DUAL UNION ALL
SELECT 3, 'Micheal', 'Palmice' FROM DUAL UNION ALL
SELECT 4, 'Jerry', 'Torchiano' FROM DUAL;
CREATE TABLE items
(PRODUCT_ID, PRODUCT_NAME, PRICE) AS
SELECT 100, 'Black Shoes', 79.99 FROM DUAL UNION ALL
SELECT 101, 'Brown Pants', 111.99 FROM DUAL UNION ALL
SELECT 102, 'White Shirt', 10.99 FROM DUAL;
CREATE TABLE purchases(
PURCHASE_ID NUMBER GENERATED BY DEFAULT AS IDENTITY (START WITH 1) NOT NULL,
CUSTOMER_ID NUMBER,
PRODUCT_ID NUMBER,
QUANTITY NUMBER,
PURCHASE_DATE TIMESTAMP
);
INSERT INTO purchases
(CUSTOMER_ID, PRODUCT_ID, QUANTITY, PURCHASE_DATE)
SELECT 1, 101, 3, TIMESTAMP'2022-10-11 09:54:48' FROM DUAL UNION ALL
SELECT 1, 100, 1, TIMESTAMP '2022-10-12 19:04:18' FROM DUAL UNION ALL
SELECT 2, 101,1, TIMESTAMP '2022-10-11 09:54:48' FROM DUAL UNION ALL
SELECT 2, 101, 3, TIMESTAMP '2022-10-17 19:34:58' FROM DUAL UNION ALL
SELECT 2, 102, 3,TIMESTAMP '2022-12-06 11:41:25' + NUMTODSINTERVAL ( LEVEL * 2, 'DAY') FROM dual CONNECT BY LEVEL <= 6 UNION ALL
SELECT 2, 102, 3,TIMESTAMP '2022-12-26 11:41:25' + NUMTODSINTERVAL ( LEVEL * 2, 'DAY') FROM dual CONNECT BY LEVEL <= 6 UNION ALL
SELECT 3, 101,1, TIMESTAMP '2022-12-21 09:54:48' FROM DUAL UNION ALL
SELECT 3, 102,1, TIMESTAMP '2022-12-27 19:04:18' FROM DUAL UNION ALL
SELECT 3, 102, 4,TIMESTAMP '2022-12-22 21:44:35' + NUMTODSINTERVAL ( LEVEL * 2, 'DAY') FROM dual
CONNECT BY LEVEL <= 15 UNION ALL
SELECT 3, 101,1, TIMESTAMP '2022-12-11 09:54:48' FROM DUAL UNION ALL
SELECT 3, 102,1, TIMESTAMP '2022-12-17 19:04:18' FROM DUAL UNION ALL
SELECT 3, 102, 4,TIMESTAMP '2022-12-12 21:44:35' + NUMTODSINTERVAL ( LEVEL * 2, 'DAY') FROM dual
CONNECT BY LEVEL <= 5;
ALTER TABLE customers
ADD CONSTRAINT customers_pk PRIMARY KEY (customer_id);
ALTER TABLE items
ADD CONSTRAINT items_pk PRIMARY KEY (product_id);
ALTER TABLE purchases
ADD CONSTRAINT purchases_pk PRIMARY KEY (purchase_id);
ALTER TABLE purchases ADD CONSTRAINT customers_fk FOREIGN KEY (customer_id) REFERENCES customers(customer_id);
ALTER TABLE purchases ADD CONSTRAINT items_fk FOREIGN KEY (PRODUCT_ID) REFERENCES items(product_id);
/* works fine */
SELECT TO_CHAR (p.purchase_date, 'IYYY"W"IW') AS year_week
, p.customer_id
, c.first_name
, c.last_name
, SUM (p.quantity * i.price) AS total_amt
FROM purchases p
JOIN customers c ON p.customer_id = c.customer_id
JOIN items i ON p.product_id = i.product_id
GROUP BY GROUPING SETS ( (TO_CHAR (p.purchase_date, 'IYYY"W"IW'), p.customer_id, c.first_name, c.last_name)
, (TO_CHAR (p.purchase_date, 'IYYY"W"IW'))
, ()
)
ORDER BY TO_CHAR (p.purchase_date, 'IYYY"W"IW'), p.customer_id;
YEAR_WEEK
CUSTOMER_ID
FIRST_NAME
LAST_NAME
TOTAL_AMT
2022W41
1
Faith
Mazzarone
415.96
2022W41
2
Lisa
Saladino
111.99
2022W41
-
-
-
527.95
2022W42
2
Lisa
Saladino
335.97
2022W42
-
-
-
335.97
2022W49
2
Lisa
Saladino
65.94
2022W49
3
Micheal
Palmice
111.99
2022W49
-
-
-
177.93
2022W50
2
Lisa
Saladino
131.88
2022W50
3
Micheal
Palmice
142.87
2022W50
-
-
-
274.75
2022W51
3
Micheal
Palmice
243.87
2022W51
-
-
-
243.87
2022W52
2
Lisa
Saladino
98.91
2022W52
3
Micheal
Palmice
186.83
2022W52
-
-
-
285.74
2023W01
2
Lisa
Saladino
98.91
2023W01
3
Micheal
Palmice
131.88
2023W01
-
-
-
230.79
2023W02
3
Micheal
Palmice
175.84
2023W02
-
-
-
175.84
2023W03
3
Micheal
Palmice
131.88
2023W03
-
-
-
131.88
-
-
-
-
2384.72
/* unexpected output */
SELECT p.customer_id,
c.first_name,
c.last_name,
TO_CHAR (p.purchase_date, 'IYYY"W"IW') AS year_week,
SUM (p.quantity * i.price) AS total_amt
FROM purchases p
JOIN customers c ON p.customer_id = c.customer_id
JOIN items i ON p.product_id = i.product_id
GROUP BY GROUPING SETS (
(p.customer_id, c.first_name, c.last_name),
(TO_CHAR (p.purchase_date, 'IYYY"W"IW')),
(p.customer_id, c.first_name, c.last_name)
, ()
)
ORDER BY p.customer_id,
TO_CHAR (p.purchase_date, 'IYYY"W"IW');

Answer 1

SELECT p.customer_id,
c.first_name,
c.last_name,
TO_CHAR (p.purchase_date, 'IYYY"W"IW') AS year_week,
SUM (p.quantity * i.price) AS total_amt
FROM purchases p
JOIN customers c ON p.customer_id = c.customer_id
JOIN items i ON p.product_id = i.product_id
GROUP BY GROUPING SETS (
(p.customer_id, c.first_name, c.last_name, (TO_CHAR (p.purchase_date, 'IYYY"W"IW')))
, p.customer_id
, ()
)
ORDER BY p.customer_id,
TO_CHAR (p.purchase_date, 'IYYY"W"IW');
CUSTOMER_ID FIRST_NAME LAST_NAME YEAR_WEEK TOTAL_AMT
1 Faith Mazzarone 2022W41 415.96
1 - - - 415.96
2 Lisa Saladino 2022W41 111.99
2 Lisa Saladino 2022W42 335.97
2 Lisa Saladino 2022W49 65.94
2 Lisa Saladino 2022W50 131.88
2 Lisa Saladino 2022W52 98.91
2 Lisa Saladino 2023W01 98.91
2 - - - 843.6
3 Micheal Palmice 2022W49 111.99
3 Micheal Palmice 2022W50 142.87
3 Micheal Palmice 2022W51 243.87
3 Micheal Palmice 2022W52 186.83
3 Micheal Palmice 2023W01 131.88
3 Micheal Palmice 2023W02 175.84
3 Micheal Palmice 2023W03 131.88
3 - - - 1125.16
- - - - 2384.72