分组依据与最大日期和另一列

Question

I have the following table.

id	user_id	file_id	completed	updated
1	161	10	1	2022-10-11
2	164	11	1	2022-10-12
3	161	10	1	2022-10-12
4	167	10	1	2022-10-10
5	167	10	1	2022-10-11
6	167	10	1	2022-10-12

I want to select the row for each user having the max updated date for each file_id .

SELECT * FROM user_file
WHERE updated = (SELECT uf.updated FROM user_file uf GROUP BY uf.user_id,uf.file_id)

I have come up with this query but it returns an error "Subquery returns more than 1 row"

Answer 1

Maybe you want to check these out?

• SQL select only rows with max value on a column
• Retrieving the last record in each group - MySQL

Personally prefer the window function solution

SELECT a.*
  FROM (SELECT id, user_id, file_id, ...
               ROW_NUMBER() OVER (PARTITION BY file_id ORDER BY updated DESC) ranked_order
          FROM user_file) a
 WHERE a.ranked_order = 1