How to find the second minimum log in time per each user id

Question

I'm working on a SQL query on BigQuery and trying to find the second minimum login time for each user id.

User_id	LoginTime
1	2022-11-06 08:45:17
1	2022-11-07 09:52:27
1	2022-11-08 02:08:54
2	2022-11-04 08:10:38
2	2022-11-07 16:46:34
2	2022-11-18 01:26:53

And I want to find the following result.

User_id	SecondLoginTime
1	2022-11-07 09:52:27
2	2022-11-07 16:46:34

Could anyone help me figure out how to approach this problem?

Answer 1

We can use the RANK() analytic function:

WITH cte AS (
    SELECT *, RANK() OVER (PARTITION BY User_id ORDER BY LoginTime) rnk
    FROM yourTable
)

SELECT User_id, LoginTime AS SecondLoginTime
FROM cte
WHERE rnk = 2
ORDER BY User_id;

Note that, depending on the behavior you want if ties can happen, you may want to use DENSE_RANK() instead of RANK() .