Question

i have two tables

item_tb

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

user_tb

| user_id | user_name |
-----------------------

in item_tb i have lots of items that belongs to various user in user_tb, an item can belong to one or more users…

so, given the userid A and userid B how can I do a mysql query to select all the items the belong both to userA and userB?

Answer 1

    select i.item_id
      from item_tb i
inner join user_tb u ON i.user_id = u.user_id
     where i.user_id IN (42, 43)
  group by i.item_id
    having count(*) = 2

Where 42 and 43 are those users.