Laravel Eloquent find rows with one common unknown field

Question

I have one table

inbox

| inboxid   | user_id  |
| SDFHK2D   | 123      | 
| SDFHK2D   | 124      | 
| GGGFHK2   | 125      |
| GGGFHK2   | 126      |  

What I want to fetch is:

Records which is common for both users from inbox table only. (AGAIN NO JOIN) Something like this

Select * 
from inbox
where [ user_id = 123 , user_id = 124 ] 
AND inboxid is COMMON

So basically I want to fetch all inbox id's which are common between user 123 and user 124

How can I do it with Laravel Eloquent or by simple SQL query?

Result Required 

| inboxid   | p_user_id |  s_user_id  | 
| SDFHK2D   | 123       |  124        | 

Answer 1

Do a GROUP BY, use HAVING to make sure both 123 and 124 are there:

select inboxid, min(user_id) as p_user_id, max(user_id) as s_user_id  
from inbox
where user_id in (123, 124)
group by inboxid
having count(distinct user_id) > 1

If you also want other pairs than 123/124 having the same inboxid, simply skip the WHERE clause.