mysql - Writing a SQL query that gets information from 3 different tables -

i cant seem figure out how write these 2 queries on tables have created. 2 queries trying write

find users have reviewed both shops , restaurants.  find users reviewed businesses, not shops or restaurants. 

the tables using

 reviews; +-------------+---------+------+-----+---------+-------+ | field       | type    | null | key | default | | +-------------+---------+------+-----+---------+-------+ | business_id | int(11) | no   | pri | null    |       | | user_id     | int(11) | no   | pri | null    |       | | review_id   | int(11) | no   | pri | null    |       |  | review_date | date    | yes  |     | null    |       | | star_rating | int(1)  | yes  |     | 1       |        businesses +--------------+--------------+------+-----+---------+-------+ | field        | type         | null | key | default | | +--------------+--------------+------+-----+---------+-------+ | business_id  | int(11)      | no   | pri | null    |       | | name         | varchar(50)  | yes  |     | null    |       | | city         | varchar(40)  | yes  |     | null    |       | | state        | varchar(20)  | yes  |     | null    |       | | full_address | varchar(120) | yes  |     | null    |       |  users; +------------+-------------+------+-----+---------+-------+ | field      | type        | null | key | default | | +------------+-------------+------+-----+---------+-------+ | user_id    | int(11)     | no   | pri | null    |       | | name       | varchar(50) | yes  |     | null    |       | | user_since | date        | yes  |     | null    explain is_a_restaurant;  +--------------+-------------+------+-----+---------+-------+  | field        | type        | null | key | default | |    +--------------+-------------+------+-----+---------+-------+ | business_id  | int(11)     | no   | pri | null    |       | | cuisine_type | varchar(20) | yes  |     | null    |       | | total_seats  | int(11)     | yes  |     | 1       |       | +--------------+-------------+------+-----+---------+-------+  explain is_a_shop;  +-------------+-------------+------+-----+---------+-------+  | field       | type        | null | key | default | |  +-------------+-------------+------+-----+---------+-------+  | business_id | int(11)     | no   | pri | null    |       |  | shop_type   | varchar(50) | yes  |     | null    |       | 

i dont know start. know going join businesses business id dont know how going find people reviewed both shops , restaurants. can help?

edit: have tried

for first query: find users have reviewed both shops , restaurants.

 select b.business_id  is_a_shop b   join reviews r  on r.business_id = b.business_id  join is_a_restaurant k  on r.business_id = k.business_id; 

here's first 1 should like: can change select statement based on info want see.

select u.name users u inner join reviews rev on rev.user_id = u.user_id  exists (select * is_a_shop s s.business_id = rev.business_id)  or exists (select * is_a_restaurant r r.business_id = rev.business_id) 

this pulls users wrote reviews business_id found in is_a_shop table or is_a_restaurant. should able figure out second query this.