Everything Dev Needs to Know About SQL Server DateTimeOffset

Hey Dev, are you looking to understand how to work with dates and times in SQL Server? Well, you’re in the right place! In this article, we’ll be discussing everything you need to know about the DateTimeOffset datatype in SQL Server.

What is the DateTimeOffset datatype?

The DateTimeOffset datatype is used to store date and time values, including the time zone offset from UTC (Coordinated Universal Time). This differs from the DateTime datatype, which does not store time zone information.

The DateTimeOffset datatype is particularly useful for applications that deal with global data, as it allows you to easily convert date and time values between time zones.

How does it work?

When you store a value in a DateTimeOffset column, SQL Server stores the date and time as well as the time zone offset. The offset is added to the date and time to produce a UTC value, which is then stored in the database.

This means that if you retrieve a value from a DateTimeOffset column, SQL Server will automatically convert the UTC value back to your local time zone.

Example:

Date and Time	Time Zone Offset	UTC Value
2022-01-01 12:00:00	+01:00	2022-01-01 11:00:00
2022-01-01 12:00:00	-05:00	2022-01-01 17:00:00

In the first row of the table, the time zone offset is +01:00, which means that the UTC value is 2022-01-01 11:00:00. If you retrieve this value from the database, SQL Server will automatically convert it to your local time zone, which might be +02:00.

In the second row of the table, the time zone offset is -05:00, which means that the UTC value is 2022-01-01 17:00:00. If you retrieve this value from the database, SQL Server will automatically convert it to your local time zone, which might be -03:00.

How to use the DateTimeOffset datatype

Using the DateTimeOffset datatype in SQL Server is relatively simple. To define a column as a DateTimeOffset datatype, you simply need to include the OFFSET keyword in the column definition.

Example:

CREATE TABLE myTable ( myDate DateTimeOffset )

Once you have defined a column as a DateTimeOffset datatype, you can insert values into the column just like you would with any other date or time datatype.

Example:

INSERT INTO myTable (myDate) VALUES (‘2022-01-01 12:00:00 +01:00’)

You can also perform all of the usual date and time operations on values stored in a DateTimeOffset column, including adding and subtracting values, comparing values, and formatting values.

FAQ

Q: Can I use the DateTimeOffset datatype with older versions of SQL Server?

A: The DateTimeOffset datatype was introduced in SQL Server 2008, so if you are using an older version of SQL Server, you will not be able to use this datatype.

Q: Can I convert values between DateTimeOffset and DateTime datatypes?

A: Yes, you can convert values between the DateTimeOffset and DateTime datatypes using the CAST or CONVERT functions. However, when you convert a value from a DateTimeOffset datatype to a DateTime datatype, the time zone information will be lost.

Q: How do I specify a time zone in a DateTimeOffset value?

A: When you insert a value into a DateTimeOffset column, you need to specify the date and time as well as the time zone offset. The offset can be specified using the + or – sign followed by the hours and minutes of the offset.

Q: Can I use DateTimeOffset values in dynamic SQL?

A: Yes, you can use DateTimeOffset values in dynamic SQL just like you would with any other value. However, you need to make sure that you properly escape the value to avoid SQL injection attacks.

Q: Can I use the BETWEEN operator with DateTimeOffset values?

A: Yes, you can use the BETWEEN operator with DateTimeOffset values just like you would with any other value. However, you need to make sure that you take time zone offsets into account when specifying the range.

Q: Can I change the time zone offset of a DateTimeOffset value?

A: Yes, you can change the time zone offset of a DateTimeOffset value using the SWITCHOFFSET function. This function takes two arguments: the original DateTimeOffset value, and the new time zone offset.

Conclusion

Overall, the DateTimeOffset datatype is a powerful tool for working with dates and times in SQL Server. By storing both the date and time as well as the time zone offset, you can easily work with a wide range of time zones and ensure that you are always storing and retrieving accurate date and time values.