Understanding Datetime and Offset in SQL Server

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As data professionals, we often work with date and time data in our applications. In many cases, we need to store or manipulate dates and times that include an offset from UTC (Coordinated Universal Time). In this article, we’ll explore how to insert datetime values with offsets into a SQL Server database.

Introduction

SQL Server provides several data types for storing date and time information, but one of the most commonly used is datetimeoffset. This data type allows us to store dates and times along with an offset from UTC. In this article, we’ll delve into the world of datetimeoffset, exploring its usage, limitations, and best practices.

Understanding Datetimeoffset

The datetimeoffset data type in SQL Server represents a date and time value that includes both a date component and an offset from UTC. The format is as follows:

YYYY-MM-DD HH:MM:SS.mmmmmm-ff

Where:

• YYYY-MM-DD is the date component
• HH:MM:SS is the time component
• mmmmmm is a fractional second value (typically 6 digits)
• ff is the offset from UTC in hours and minutes, separated by a hyphen

For example, the following datetimeoffset value represents June 16th, 2020, at 13:41:36.000Z:

2020-06-16T13:41:36.000Z

Choosing the Correct Datatype

When choosing a data type for your datetime column, you have several options:

• datetime: This data type represents a date and time value without an offset from UTC. While it’s suitable for most applications, it may not meet the requirements of certain business cases.
• datetime2: Similar to datetime, but with a narrower range (from 1 January 1900 00:00:00 to 31 December 9999 23:59:59).
• datetimeoffset: As discussed earlier, this data type represents a date and time value along with an offset from UTC.

For most use cases, we recommend using datetimeoffset. This allows us to take advantage of SQL Server’s built-in functionality for working with datetime values that include offsets.

Inserting Datetime Values into the Database

To insert a datetimevalue with an offset into your database, follow these steps:

1. Create a table with a datetimeoffset column:

create table t (ts datetimeoffset);

2.  Insert a value into the table using the following syntax:

    ```markdown
insert into t (ts) values ('2020-06-16T13:41:36.000Z');

3. Query the inserted value using the select statement, as shown below:

select * from t;

## Formatting Datetime Values
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When working with datetime values in SQL Server, we often need to format them for display or storage purposes. Here are some ways to achieve this:

### Using Convert()

We can use the `convert()` function with option 127 to convert a datetimevalue to a string in a specific format.

```markdown
select convert(varchar(255), t.ts, 127) from t;

This will output the value in the following format: 2020-06-16 13:41:36.0000000.

Using Format()

Alternatively, we can use the format() function to achieve the same result.

select format(t.ts, 'yyyy-MM-dd hh:mm:ss.ffffff') from t;

This will output the value in the following format: 2020-06-16 13:41:36.0000000.

Using Format() with Custom Patterns

The format() function also supports custom patterns for formatting datetime values.

select format(t.ts, 'yyyy-MM-dd hh:mm:ss zzz') from t;

This will output the value in the following format: 2020-06-16 13:41:36 -05:00.

Adding Datetimeoffset Column with Custom Format

Sometimes we might want to store datetime values in a custom format. We can achieve this by adding a new column to our table definition.

alter table t add ts_iso8601 as (convert(varchar(255), t.ts, 127));

This will create a new column called ts_iso8601 that stores the value in the yyyy-MM-dd hh:mm:ss.ffffff format.

Conclusion

In this article, we explored how to insert datetime values with offsets into a SQL Server database using the datetimeoffset data type. We also discussed various ways to format these values for display or storage purposes.

By following these guidelines and best practices, you can effectively work with datetime values that include offsets in your SQL Server applications.

Additional Resources

• SQL Server documentation: Learn more about the format() function and its usage.
• DB<>fiddle example: Test out the code examples provided in this article using a DB<>fiddle.

Common Pitfalls

• Inconsistent data formats: Make sure to use a consistent format for storing and retrieving datetime values.
• Incorrect offset assumptions: Be aware of potential issues with date and time calculations when working with datetime values that include offsets.

Last modified on 2023-11-06