Understanding SQL Server Datetime Format

Hello, Dev! In this article, we will discuss everything you need to know about the datetime format in SQL Server. Datetime format is a crucial aspect of any database system. Understanding and properly using it can significantly improve the accuracy and efficiency of your system.

What is Datetime Format?

Datetime format is a standard way of representing date and time information in a database system. It allows users to store, manipulate, and retrieve date and time values accurately and efficiently. SQL Server supports various datetime data types, including datetime, smalldatetime, and datetimeoffset. Each data type has its own format and precision, which we will discuss in this article.

Datetime

The datetime data type in SQL Server is used to represent date and time values with a precision of up to three and a half digits for seconds (milliseconds). The format for this data type is YYYY-MM-DD HH:MI:SS. For example, ‘2022-08-19 21:30:45’. The range of datetime data type is from January 1, 1753, to December 31, 9999.

The following table shows the minimum and maximum datetime values supported by SQL Server:

Minimum Value	1753-01-01 00:00:00
Maximum Value	9999-12-31 23:59:59.997

It is essential to note that SQL Server stores datetime values as 8 bytes, with the first four bytes representing the number of days since January 1, 1900, and the second four bytes representing the number of milliseconds since midnight.

Smalldatetime

The smalldatetime data type is similar to datetime but with a precision of up to a minute. The format for this data type is YYYY-MM-DD HH:MI. For example, ‘2022-08-19 21:30’. The range of smalldatetime data type is from January 1, 1900, to June 6, 2079.

The following table shows the minimum and maximum smalldatetime values supported by SQL Server:

Minimum Value	1900-01-01 00:00:00
Maximum Value	2079-06-06 23:59:00

Datetimeoffset

The datetimeoffset data type was introduced in SQL Server 2008. It is used to represent datetime values with an offset from UTC time. The format for this data type is YYYY-MM-DD HH:MI:SS[.nnnnnnn][{+|-}hh:mm]. For example, ‘2022-08-19 21:30:45.1234567 +05:30’. The range of datetimeoffset data type is from January 1, 0001, to December 31, 9999.

The following table shows the minimum and maximum datetimeoffset values supported by SQL Server:

Minimum Value	0001-01-01 00:00:00.0000000 -14:00
Maximum Value	9999-12-31 23:59:59.9999999 +14:00

Using Datetime Format in SQL Server

Now that we understand the different datetime data types and their formats let’s discuss how to use them in SQL Server. To insert a datetime value in SQL Server, you can use the following syntax:

INSERT INTO Table_Name (Column_Name) VALUES ('YYYY-MM-DD HH:MI:SS')

To retrieve a datetime value from SQL Server, you can use the following syntax:

SELECT Column_Name FROM Table_Name WHERE Column_Name = 'YYYY-MM-DD HH:MI:SS'

It is essential to ensure that the datetime value is in the correct format; otherwise, the system will return an error. You can also use various SQL Server datetime functions to manipulate and format datetime values, which we will discuss in the next section.

SQL Server Datetime Functions

SQL Server provides numerous datetime functions that can be used to manipulate and format datetime values. Some of the commonly used datetime functions are:

GETDATE()

The GETDATE() function returns the current system date and time (datetime data type) in the ‘YYYY-MM-DD HH:MI:SS’ format.

Example:

SELECT GETDATE()

Output:

GETDATE()

2022-08-20 11:30:45

DATEPART()

The DATEPART() function extracts a specific part (year, month, day, etc.) of a datetime value.

Example:

SELECT DATEPART(YEAR, '2022-08-19 21:30:45')

Output:

Date_Part	Output
YEAR	2022

DATEADD()

The DATEADD() function adds a specific interval (year, month, day, etc.) to a datetime value.

Example:

SELECT DATEADD(YEAR, 1, '2022-08-19 21:30:45')

Output:

DATEADD

2023-08-19 21:30:45.000

CONVERT()

The CONVERT() function converts a datetime value from one format to another.

Example:

SELECT CONVERT(VARCHAR(10), '2022-08-19 21:30:45', 101)

Output:

CONVERT

08/19/2022

FAQs

What is the best datetime data type to use in SQL Server?

The best datetime data type to use in SQL Server depends on the specific requirements of your system. If you need high precision, you can use the datetime data type. If you need a lower precision, you can use the smalldatetime data type. If you need to store datetime values with an offset from UTC time, you can use the datetimeoffset data type.

Can I use a different format for datetime values in SQL Server?

No, SQL Server only supports the datetime formats discussed in this article. However, you can use various datetime functions to convert datetime values from one format to another.

How do I ensure that a datetime value is in the correct format before inserting it into SQL Server?

You can use various datetime functions to validate and format datetime values before inserting them into SQL Server. For example, you can use the CONVERT() function to convert a datetime value from one format to another.

How do I retrieve the current system date and time in SQL Server?

You can use the GETDATE() function to retrieve the current system date and time in SQL Server.

Can I add or subtract a specific interval (year, month, day, etc.) from a datetime value in SQL Server?

Yes, you can use the DATEADD() function to add or subtract a specific interval (year, month, day, etc.) from a datetime value in SQL Server.

Can I extract a specific part (year, month, day, etc.) of a datetime value in SQL Server?

Yes, you can use the DATEPART() function to extract a specific part (year, month, day, etc.) of a datetime value in SQL Server.

Conclusion

Datetime format is a crucial aspect of any database system. Understanding and properly using it can significantly improve the accuracy and efficiency of your system. In this article, we discussed the different datetime data types supported by SQL Server and their formats. We also discussed various datetime functions that can be used to manipulate and format datetime values. We hope this article was helpful, and you can start using datetime format correctly in your SQL Server system.