SQL 服务器上 UTC 的 datetimeoffset 与 datetime2

Question

Are there any benefits to storing a UTC timestamp in a datetimeoffset field vs datetime2? It seems they're essentially the same.

+------------------------------------+-----------------------------+
| datetimeoffset                     | datetime2                   |
|------------------------------------+-----------------------------|
| 2021-02-12 16:48:11.0677934 +00:00 | 2021-02-12 16:48:11.0677934 |
+------------------------------------+-----------------------------+

Answer 1

The datetimeoffset data type will allow comparison between different offsets of the same time. eg:

SELECT 'equal'
WHERE
    CAST('2021-02-12 15:48:11.0677934 -01:00' AS datetimeoffset) = CAST('2021-02-12 16:48:11.0677934 +00:00' AS datetimeoffset).

If you are storing only UTC values (where the offset is always zero), you can save storage space with datetime2 . datetimeoffset requires 10 bytes of storage whereas datetime needs 8 bytes for precision 5 or greater, 7 bytes for precision 3-4, and 6 bytes for precision 2 or less.