MariaDB [q]> select * from Post;

+---------+-------------+ | post_id | name | +---------+-------------+
| 1 | first post |
| 2 | vtoroi post |
| 3 | trety post |
+---------+-------------+
3 rows in set (0.001 sec)

MariaDB [q]> select * from Tag;
+--------+-------+
| tag_id | name |
+--------+-------+
| 1 | Petya |
| 2 | Vasya |
| 3 | Stas |
+--------+-------+
3 rows in set (0.001 sec)

MariaDB [q]> select * from PostTags;
+---------+--------+
| post_id | tag_id |
+---------+--------+
| 1 | 3 |
| 2 | 1 |
| 2 | 2 |
| 3 | 3 |
+---------+--------+
4 rows in set (0.002 sec)

MariaDB [q]>
все ли у меня хорошо ?

нет бы фидл накидать -.-