Question

I have table

xyz (to store the relations between user and item)

| user_id |  item_id |
----------------------

An item can belong to one or more user and viceversa.

So, given the user_id = A and user_id = B how can I do a mysql query to select all the items the belong both to user A and user B?

Answer 1

Try this one:

SELECT Item_ID
FROM xyz
WHERE  User_ID IN ('A','B')
GROUP BY Item_ID
HAVING COUNT(distinct user_id) = 2

SQLFiddle Demo