Calculated field
DATEDIFF('month',[shipped],[received])
Sample data
| shipment | shipped | received | text | year | month | day | hour | minute | second | lat | lon | wkt |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2024-12-29 | 2024-12-29T16:25:40 | 2024-12-29 | 2025 | 2 | 25 | 9 | 25 | 40 | 10 | 106 | POINT (106 10) |
| 2 | 2024-12-30 | 2024-12-30T16:25:40 | 2024-12-30 | 2025 | 2 | 26 | 10 | 25 | 40 | 10.1 | 106.1 | POINT (106.1 10.1) |
| 3 | 2025-01-01 | 2025-01-01T16:25:40 | 2025-01-01 | 2025 | 2 | 27 | 11 | 25 | 40 | 10.2 | 106.2 | POINT (106.2 10.2) |
| 4 | 2025-01-31 | 2025-01-31T16:25:40 | 2025-01-31 | 2025 | 2 | 28 | 12 | 25 | 40 | 10.3 | 106.3 | POINT (106.3 10.3) |
| 5 | 2025-02-28 | 2025-02-28T16:25:40 | 2025-02-28 | 2025 | 2 | 29 | 13 | 25 | 40 | 10.4 | 106.4 | POINT (106.4 10.4) |
| 6 | 2025-03-15 | 2025-03-15T16:25:40 | 2025-03-15 | 2025 | 2 | 30 | 14 | 25 | 40 | 10.5 | 106.5 | POINT (106.5 10.5) |
| 7 | null | null | null | 2025 | 2 | 31 | 15 | 25 | 40 | 10.6 | 106.6 | POINT (106.6 10.6) |
| 8 | 2024-02-29 | 2024-02-29T16:25:40 | 2024-02-29 | 2025 | 2 | 32 | 16 | 25 | 40 | 10.7 | 106.7 | POINT (106.7 10.7) |
The same calculation as SQL
SELECT date_diff('month',shipped,received) AS result FROM input ORDER BY shipmentRuns the example above.
SELECT DATEDIFF(month,shipped,received) AS result FROM input ORDER BY shipment
Written for this dialect; not run here.
SELECT DATE_DIFF(DATE(received),shipped,MONTH) AS result FROM input ORDER BY shipment
Written for this dialect; not run here.
Result
| shipment | shipped | received | text | result |
|---|---|---|---|---|
| 1 | 2024-12-29 | 2024-12-29T16:25:40 | 2024-12-29 | 0 |
| 2 | 2024-12-30 | 2024-12-30T16:25:40 | 2024-12-30 | 0 |
| 3 | 2025-01-01 | 2025-01-01T16:25:40 | 2025-01-01 | 0 |
| 4 | 2025-01-31 | 2025-01-31T16:25:40 | 2025-01-31 | 0 |
| 5 | 2025-02-28 | 2025-02-28T16:25:40 | 2025-02-28 | 0 |
| 6 | 2025-03-15 | 2025-03-15T16:25:40 | 2025-03-15 | 0 |
| 7 | null | null | null | null |
| 8 | 2024-02-29 | 2024-02-29T16:25:40 | 2024-02-29 | 0 |
Same rows from the calculation and from the SQL in DuckDB.
Where a naive translation goes wrong
- Month difference counts month boundaries rather than completed thirty-day periods.
Naive SQL
SELECT floor(date_diff('day',shipped,shipped+INTERVAL '1 day')/30) AS result FROM input ORDER BY shipmentshipment shipped received text result 1 2024-12-29 2024-12-29T16:25:40 2024-12-29 0 2 2024-12-30 2024-12-30T16:25:40 2024-12-30 0 3 2025-01-01 2025-01-01T16:25:40 2025-01-01 0 4 2025-01-31 2025-01-31T16:25:40 2025-01-31 0 5 2025-02-28 2025-02-28T16:25:40 2025-02-28 0 6 2025-03-15 2025-03-15T16:25:40 2025-03-15 0 7 null null null null 8 2024-02-29 2024-02-29T16:25:40 2024-02-29 0 Matches the calculation
SELECT date_diff('month',shipped,shipped+INTERVAL '1 day') AS result FROM input ORDER BY shipmentshipment shipped received text result 1 2024-12-29 2024-12-29T16:25:40 2024-12-29 0 2 2024-12-30 2024-12-30T16:25:40 2024-12-30 0 3 2025-01-01 2025-01-01T16:25:40 2025-01-01 0 4 2025-01-31 2025-01-31T16:25:40 2025-01-31 1 5 2025-02-28 2025-02-28T16:25:40 2025-02-28 1 6 2025-03-15 2025-03-15T16:25:40 2025-03-15 0 7 null null null null 8 2024-02-29 2024-02-29T16:25:40 2024-02-29 1
Signature
DATEDIFF(date_part, date1, date2, [start_of_week])