Postgres 14

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CREATE TABLE purchase
(
id SERIAL PRIMARY KEY,
sku TEXT NOT NULL,
date DATE NOT NULL
)
INSERT INTO Purchase(sku, date) VALUES('A123','10/02/2022');
INSERT INTO Purchase(sku, date) VALUES('C123','13/02/2022');
INSERT INTO Purchase(sku, date) VALUES('A123','11/02/2022');
INSERT INTO Purchase(sku, date) VALUES('B123','13/02/2022');
INSERT INTO Purchase(sku, date) VALUES('C123','13/02/2022');
INSERT INTO Purchase(sku, date) VALUES('A123','10/02/2022');
1 rows affected

1 rows affected

1 rows affected

1 rows affected

1 rows affected

1 rows affected

SELECT id, sku, date 
FROM (
  select *, row_number() over(partition by sku order by id) rn
  from purchase
)p
where rn <= 2;


id
sku
date


1
A123
2022-02-10

3
A123
2022-02-11

4
B123
2022-02-13

2
C123
2022-02-13

5
C123
2022-02-13

id	sku	date
1	A123	2022-02-10
3	A123	2022-02-11
4	B123	2022-02-13
2	C123	2022-02-13
5	C123	2022-02-13