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| date | id |
|---|---|
| 2021-01-01 | 1 |
| 2021-01-02 | 1 |
| 2021-01-03 | 1 |
| 2021-01-04 | 1 |
| 2021-01-05 | 2 |
| 2021-01-06 | 2 |
| 2021-01-07 | 2 |
| 2021-01-08 | 2 |
| 2021-01-09 | 2 |
| 2021-01-10 | 2 |
| 2021-01-11 | 2 |
| 2021-01-12 | 2 |
| 2021-01-13 | 2 |
| 2021-01-14 | 2 |
| 2021-01-15 | 2 |
| 2021-01-16 | 2 |
| 2021-01-17 | 2 |
| 2021-01-18 | 2 |
| 2021-01-19 | 2 |
| 2021-01-20 | 2 |
| 2021-01-21 | 2 |
| 2021-01-22 | 2 |
| 2021-01-23 | 2 |
| 2021-01-24 | 2 |
| 2021-01-25 | 2 |
| 2021-01-26 | null |
| 2021-01-27 | null |
| 2021-01-28 | null |
| 2021-01-29 | null |
| 2021-01-30 | null |
| 2021-01-31 | null |
SELECT 31