```
mysql> select * from product;
+------------+---------------+
| product_id | name          |
+------------+---------------+
|          1 | Car           | 
|          2 | House         | 
|          3 | Cat           | 
|          4 | Blank Product | 
+------------+---------------+
4 rows in set (0.00 sec)

mysql> select * from tag;
+--------+-----------+
| tag_id | name      |
+--------+-----------+
|      1 | Expensive | 
|      2 | Fast      | 
|      3 | Mean      | 
|      4 | Large     | 
|      5 | Small     | 
|      6 | Alive     | 
|      7 | Blank Tag | 
+--------+-----------+
7 rows in set (0.00 sec)

mysql> select * from product_tag;
+------------+--------+
| product_id | tag_id |
+------------+--------+
|          1 |      1 | 
|          1 |      2 | 
|          1 |      3 | 
|          1 |      4 | 
|          2 |      1 | 
|          2 |      4 | 
|          3 |      2 | 
|          3 |      3 | 
|          3 |      5 | 
|          3 |      6 | 
+------------+--------+
10 rows in set (0.00 sec)

```

Why does the following query return my blank tag but not my blank product?

```
mysql> select * from product_tag right join product using (product_id)
                                 right join tag using (tag_id);
+--------+-----------+------------+-------+
| tag_id | name      | product_id | name  |
+--------+-----------+------------+-------+
|      1 | Expensive |          1 | Car   | 
|      1 | Expensive |          2 | House | 
|      2 | Fast      |          1 | Car   | 
|      2 | Fast      |          3 | Cat   | 
|      3 | Mean      |          1 | Car   | 
|      3 | Mean      |          3 | Cat   | 
|      4 | Large     |          1 | Car   | 
|      4 | Large     |          2 | House | 
|      5 | Small     |          3 | Cat   | 
|      6 | Alive     |          3 | Cat   | 
|      7 | Blank Tag |       NULL | NULL  | 
+--------+-----------+------------+-------+
11 rows in set (0.00 sec)

```