How to get row numbers without duplicating - sql

Question

I want to get row numbers from list. I tried ROW_NUMBER() and DENSE_RANK with different variations, getting just duplicated rows.
With my code (code is below) SQL returns list of all orders, which are including some product id's of order 20 (those three products '1013', '1024', '1025').
Problem is when I try to get row_numbers out of that list, it duplicate some rows because there are more than one product including in that order.
With my code it look like this:
Order_number
20
22
27
With ROW_NUMBER() it looks like this and that is problem:
Row_number | Order_number
1 20
2 20
3 20
4 22
5 27
6 27
I want it look like this:
Row_number | Order_number
1 20
2 22
3 27
SELECT DISTINCT ORDER_ID AS 'ORDERS, WHICH HAVE AT LEAST ONE PRODUCT OF ORDER 20'
FROM ORDERS
INNER JOIN STORAGE ON ORDERS.PRODUCT_ID = STORAGE.PRODUCT_ID
WHERE STORAGE.PRODUCT_ID IN ('1013', '1024', '1025');

Answer 1

I would suggest using exists, so you don't have to deal with duplicate elimination:
SELECT o.ORDER_ID
FROM ORDERS o
WHERE EXISTS (SELECT 1
FROM STORAGE S
WHERE o.PRODUCT_ID = s.PRODUCT_ID AND
s.PRODUCT_ID IN (1013, 1024, 1025)
);
With an index on STORAGE(ORDER_ID, PRODUCT_ID) this should have very good performance.
You can also do this directly using aggregation on STORAGE:
SELECT s.ORDER_ID
FROM STORAGE S
WHERE s.PRODUCT_ID IN (1013, 1024, 1025)
GROUP BY s.ORDER_ID;

Answer 2

1.Get your distinct ORDER_ID first, then number:
SELECT ROW_NUMBER() OVER (ORDER BY ORDER_ID), ORDER_ID
FROM
(
SELECT ORDER_ID
FROM ORDERS
INNER JOIN STORAGE ON ORDERS.PRODUCT_ID = STORAGE.PRODUCT_ID
WHERE STORAGE.PRODUCT_ID IN ('1013', '1024', '1025')
GROUP BY ORDER_ID
) dt
2.Don't join to STORAGE table, instead use a correlated subquery
SELECT ROW_NUMBER() OVER (PARTITION BY ORDER_ID), ORDER_ID
FROM ORDERS o
WHERE EXISTS
(
SELECT 1
FROM STORAGE s
WHERE s.PRODUCT_ID IN ('1013', '1024', '1025')
AND s.PRODUCT_ID = o.PRODUCT_ID
) dt
3.Use DENSE_RANK() (haven't tested since you don't say what RDBMS you are using, but it may work)
SELECT DISTINCT DENSE_RANK() OVER (ORDER BY ORDER_ID), ORDER_ID
FROM ORDERS
INNER JOIN STORAGE ON ORDERS.PRODUCT_ID = STORAGE.PRODUCT_ID
WHERE STORAGE.PRODUCT_ID IN ('1013', '1024', '1025')