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| post_id | category |
|---|---|
| 1 | car |
| 1 | bed |
| 2 | car |
| 3 | bed |
| 3 | car |
| 4 | car |
| 4 | bicycle |
| 5 | car |
| 5 | bicycle |
| 5 | bed |
| 6 | bicycle |
| 6 | car |
| post_id | cat_list |
|---|---|
| 1 | bed,car |
| 3 | bed,car |
| 4 | bicycle,car |
| 6 | bicycle,car |