How can I convert a Sql Server 2008 DateTimeOffset to a DateTime

Question

I\'m hoping to convert a table which has a DATETIMEOFFSET field, down to a DATETIME field BUT recalculates the time by taking notice of the offset.

Answer 1

Note: The timezone information is discarded in conversion if no style ("126" here) is specified. It might also be discarded in some of the other styles, I don't know -- in any case the following correctly adjusts for the TZ information. See CAST and CONVERT.

select convert(datetime, cast('2008-12-19 17:30:09.0000000 +11:00' as datetimeoffset), 126) as utc;

Happy SQL'ing.

Edit

Not sure if it matters but ... datetime Can't actually store that level of precision/accuracy. If the above is run the fractional seconds will be truncated to 3 digits (and accuracy is less than that). The same-same with datetime2 (and datetimeoffset(7)) produces a non-truncated value:

select convert(datetime2, cast('2008-12-19 17:30:09.1234567 +11:00' as datetimeoffset(7)), 126) as utc;