Laravel-选择第一个出现列值的行

Question

I have DB table urls similar to this

id | user_id | name
----------------------------
1  | 56      | John
2  | 25      | Carry
3  | 56      | Jim
4  | 12      | Jolana
5  | 12      | Ava 

What I need to do is to select the rows with the first occurance of user_id ordered in DESC by id . In this case it would mean to select rows with IDs 5 , 3 and 2 .

Can this be achieved somehow using Eloquent, or if not, pure SQL? I can imagine writing a script for this but I would like to make it work with one query.

Answer 1

This is easy to do with SQL:

select t.*
from t
where t.id = (select min(t2.id) from t t2 where t2.user_id = t.user_id);

Answer 2

You could use ROW_NUMBER :

SELECT *
FROM (SELECT *, ROW_NUMBER() OVER(PARTITION BY user_id ORDER BY id DESC) AS rn
      FROM tab_name) sub
WHERE rn = 1
ORDER BY id DESC;

DBFiddle Demo - MariaDB 10.2

DBFiddle Demo - MySQL 8.0