__________________________
| id | email   | password |
|-------------------------|
| 1  | a@g.com | 123      |
| 2  | b@g.com | 123      |
| 3    c@g.com | 123      |
| 4    d@g.com | 123      |
--------------------------

______________
|id |  name    |
|--------------|
|1  | customer |
|2  | retailer |
----------------

__________________
|id_user |  id_role|
|------------------|
|  1     |    1    |  -> a@gmail.com is a customer
|  2     |    2    |  -> b@gmail.com is a retailer
|  3     |    1    |  -> c@gmail.com is a customer
|  4     |    1    |  -> d@gmail.com is a customer
 ------------------

____________________
|id|  user_id| price |
|--------------------|
|1 |    1    | 10.00 | -> price claimed by a customer a@gmail.com
|2 |    2    |  5.00 | -> price claimed by a retailer b@gmail.com
|3 |    1    |  6.00 | -> price claimed by a previous customer a@gmail.com
|4 |    3    |  5.00 | -> price claimed by a customer c@gmail.com
|5 |    2    |  7.00 | -> price claimed by a previous retailer b@gmail.com // How to get this one
|6 |    3    |  8.00 | -> price claim by a customer c@gmail.com
---------------------