SQL Server Convert Date Format: A Comprehensive Guide For Devs

Welcome, Dev, to this comprehensive guide on SQL Server Convert Date Format. As a developer, you must have come across several scenarios where you need to manipulate or convert datetime values in your SQL Server database. Whether you’re dealing with user input or manipulating data for reporting purposes, it’s essential to know how to handle date formats in SQL Server effectively.

Understanding Date and Time Data Types in SQL Server

Before we dive into the specifics of SQL Server Convert Date Format, let’s first understand the different data types that SQL Server supports when working with dates and times.

Now that we are familiar with the different date and time data types, let’s jump into how to convert them to different formats.

Converting Date and Time Formats in SQL Server

Converting DATE to Other Formats

If you have a DATE column in your SQL Server table and want to convert it to a different format, you can use the CONVERT function in SQL Server. Here are some examples:

• Convert DATE to string in yyyy-mm-dd format:

SELECT CONVERT(VARCHAR(10), [date_column], 120) FROM [table_name];

• Convert DATE to string in mm/dd/yyyy format:

SELECT CONVERT(VARCHAR(10), [date_column], 101) FROM [table_name];

• Convert DATE to string in Mon dd yyyy format:

SELECT CONVERT(VARCHAR(12), [date_column], 107) FROM [table_name];

You can find all the available styles for date formatting in SQL Server in the official documentation.

Converting DATETIME to Other Formats

If you have a DATETIME column in your SQL Server table and want to convert it to a different format, you can use the CONVERT function in SQL Server. Here are some examples:

• Convert DATETIME to string in yyyy-mm-dd hh:mm:ss format:

SELECT CONVERT(VARCHAR(19), [datetime_column], 120) FROM [table_name];

• Convert DATETIME to string in mm/dd/yyyy hh:mm:ss format:

SELECT CONVERT(VARCHAR(19), [datetime_column], 101) + ' ' + CONVERT(VARCHAR(8), [datetime_column], 108) FROM [table_name];

• Convert DATETIME to string in Mon dd yyyy hh:mm AM/PM format:

SELECT CONVERT(VARCHAR(26), [datetime_column], 109) FROM [table_name];

Converting DATE and DATETIME to UNIX Timestamp

Unix timestamp is a widely used format for representing a specific point in time. It represents the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC. Here’s how to convert DATE and DATETIME values to Unix timestamp in SQL Server:

• Convert DATE to Unix timestamp:

SELECT DATEDIFF(s, '1970-01-01 00:00:00', [date_column]) AS [unix_timestamp] FROM [table_name];

• Convert DATETIME to Unix timestamp:

SELECT DATEDIFF(s, '1970-01-01 00:00:00', [datetime_column]) AS [unix_timestamp] FROM [table_name];

Converting String to DATE and DATETIME

If you have a string that represents a date or time, you can convert it to DATE or DATETIME data type in SQL Server. Here are some examples:

• Convert string in yyyy-mm-dd format to DATE:

SELECT CONVERT(DATE, '2021-08-15', 120) AS [date_value];

• Convert string in mm/dd/yyyy hh:mm:ss AM/PM format to DATETIME:

SELECT CONVERT(DATETIME, '08/15/2021 12:45:30 PM', 101) AS [datetime_value];

Dealing with Timezone in SQL Server

If you’re dealing with datetime values across different timezones, you need to take care of timezone conversions in SQL Server. SQL Server provides the AT TIME ZONE function to handle timezone conversions. Here’s how to use it:

• Convert datetime to UTC:

SELECT CONVERT(DATETIMEOFFSET, [datetime_column]) AT TIME ZONE 'UTC' AS [utc_datetime] FROM [table_name];

• Convert datetime from UTC to a specific timezone:

SELECT CONVERT(DATETIMEOFFSET, [datetime_column]) AT TIME ZONE 'Central Standard Time' AS [cst_datetime] FROM [table_name];

FAQ

Q1. Can I convert datetime values to different formats without using the CONVERT function?

No. The CONVERT function is the only way to convert datetime values to different formats in SQL Server.

Q2. Is there a limit to the number of date and time styles that I can use with the CONVERT function?

No. SQL Server supports a wide range of date and time styles that you can use with the CONVERT function.

Q3. Can I convert datetime values to Unix timestamp using the CAST function?

No. The CAST function does not support converting datetime values to Unix timestamp. You have to use the DATEDIFF function for this purpose.

Q4. How do I handle daylight saving time in SQL Server?

SQL Server automatically handles daylight saving time for you. It recognizes the daylight saving time rules of your local time zone and adjusts datetime values accordingly.

Q5. Can I set a default date format for my SQL Server database?

Yes. You can set a default date format for your SQL Server database using the SET DATEFORMAT function. The default date format applies to all date and time values that are not explicitly converted to a different format.

Conclusion

Manipulating and converting datetime values is an essential part of working with SQL Server databases. By understanding the different date and time data types in SQL Server and how to convert them to different formats, you can ensure that your queries return the correct results.

With this guide, you now have a comprehensive understanding of how to convert date and time formats in SQL Server. Feel free to explore the different date and time styles and experiment with different conversion functions to see how they can help you in your development projects.