i have those two databases:

users DB 

```
_______________________
| ID  |   username    |
-----------------------
|  1  |    JOHN       |
|  2  |    JACKSYS    |
|  3  |    GATSBY     |
|  4  |    GERARD     |
-----------------------

```

And products to sell DB for each user.

```
_______________________
| ID  |   product     |
-----------------------
|  1  |    JACKET     |
|  1  |    SOCKS      |
|  1  |    TROUSERS   |
|  2  |    SHIRT      |
-----------------------

```

How should be my query, if i want to select the first product only from each user, taking into considerations once this product is selected, it will be deleted later and another product will be as first position for every user. Appreciate your help.