SQL Server Never Ending when Join Two Tables - sql-server

Question

I have one source table in DB. I need to do group and sum to get one bridging table, extract supplier info on the other bridging table then join the two using part_number.
If I run the subqueries separately, T1 gives me 54699 records and T2 gives approx 10 times rows of T1.
Next, I do left join, I expect it should return 54699 records, but the server engine never stops and it returns 50 million records at the time I scroll down to the end. I have to stop the query manually. I realized there must something wrong with my query, but I can not figure it out. I would appreciate it if you have any ideas. Thank you!
SELECT
T1.*, T2.SUPPLIER
FROM
(SELECT
T.PART_NUMBER,T.YEAR, T.WEEK,
SUM(T.QTY_FILLED) TOTAL_FILLED,
SUM(T.QTY_ORDERED) TOTAL_ORDERED,
COUNT(T.LINE_NUMBER) ORDER_TIMES
FROM
DBO.TABLE1 T
WHERE
T.YEAR IS NOT NULL
GROUP BY
PART_NUMBER, T.YEAR, T.WEEK) T1
LEFT JOIN
(SELECT
T.PART_NUMBER, T.SUPPLIER
FROM
DBO.TABLE1 T) T2 ON T1.PART_NUMBER = T2.PART_NUMBER
ORDER BY
T1.PART_NUMBER, T1.YEAR, T1.WEEK
I also tried the window function, but still no luck.
WITH T1 AS
(
SELECT
T.PART_NUMBER,T.YEAR, T.WEEK,
SUM(T.QTY_FILLED) TOTAL_FILLED,
SUM(T.QTY_ORDERED) TOTAL_ORDERED,
COUNT(T.LINE_NUMBER) ORDER_TIMES
FROM
DBO.TABLE1 T
WHERE
T.YEAR IS NOT NULL
GROUP BY
PART_NUMBER, T.YEAR, T.WEEK
), T2 AS
(
SELECT T.PART_NUMBER, T.SUPPLIER
FROM DBO.TABLE1 T
)
SELECT
T1.*, T2.SUPPLIER
FROM
T1
LEFT JOIN
T2 ON T1.PART_NUMBER = T2.PART_NUMBER
ORDER BY
T1.PART_NUMBER, T1.YEAR, T1.WEEK

Answer 1

First of all, it not only return 54699 rows. You do a join without distinct, so the result could be the join of 50.000 x 5.000.000 rows and it depends on the value of your table.
If you use SQL 2017 or newer, try something like this:
SELECT
T.PART_NUMBER,T.YEAR, T.WEEK,
SUM(T.QTY_FILLED) TOTAL_FILLED,
SUM(T.QTY_ORDERED) TOTAL_ORDERED,
COUNT(T.LINE_NUMBER) ORDER_TIMES,
STRING_AGG (SUPPLIER, ', ') AS SUPPLIER
FROM
DBO.TABLE1 T
WHERE
T.YEAR IS NOT NULL
GROUP BY
PART_NUMBER, T.YEAR, T.WEEK