Limit join with pagination - sql

Question

These are my db tables:
Users
| id | nme |
|----|------|
| 1 | Adam |
| 2 | Bob |
| 3 | Jan |
| 4 | Nico |
Products
| id | price |
|----|-------|
| 1 | 500 |
| 2 | 700 |
| 3 | 900 |
Orders
| id | user_id | product_id |
|----|---------|------------|
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 1 | 3 |
| 7 | 3 | 1 |
| 8 | 3 | 2 |
| 9 | 3 | 3 |
| 10 | 4 | 3 |
I want to get up to 2 users, and their products bought. I came with this:
SELECT
users.id AS 'user_id', products.id AS 'product_id'
FROM
users
INNER JOIN
orders ON orders.user_id = users.id
INNER JOIN
products ON products.id = orders.product_id
ORDER BY
orders.id
OFFSET 0 ROWS FETCH NEXT 2 ROWS ONLY
But this returns:
| user_id | product_id |
|---------|------------|
| 1 | 1 |
| 1 | 2 |
What I want to get is up to 2 users, not orders. I want to get this:
| user_id | product_id |
|---------|------------|
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
Any ideas?

Answer 1

I think you don't need a JOIN among tables but only using [Orders] table along with a window function such as DENSE_RANK() as seems the most suitable to filter out to return the result set such as
;WITH cte AS
(
SELECT *,
DENSE_RANK() OVER (ORDER BY [user_id]) AS rn
FROM [Orders]
)
SELECT [user_id], [product_id]
FROM cte
WHERE rn <= 2 -- returns only two user after sorted by their ids
ORDER BY 1, 2
Demo

Answer 2

You may use DENSE_RANK function with your join query as the following:
SELECT user_id, product_id
FROM
(
SELECT U.id AS 'user_id',
P.id AS 'product_id',
DENSE_RANK() OVER (ORDER BY U.id) dr
FROM users U INNER JOIN orders O
ON O.user_id = U.id
INNER JOIN products P
ON P.id = O.product_id
) T
WHERE dr between 1 and 2
ORDER BY user_id, product_id
WHERE dr between 1 and 2 allows you to perform pagination according to the order of user ids, i.e if you want to get users from 3 to 5, it will be WHERE dr between 3 and 5.
Check this demo.