Best approach to remove time part of datetime in SQL Server

📝 The Best Approach to Remove the Time Part of DateTime in SQL Server

Are you tired of dealing with datetime fields in SQL Server that contain both a date and a time component? Do you need to remove the time portion and only work with the date? If so, you've come to the right place!

In this blog post, we will discuss the best approach to removing the time part from a datetime field in SQL Server. We will address common issues, provide easy solutions, and even explore the possibility of better methods. Let's dig in!

The Question at Hand

The question posed was, "Which method provides the best performance when removing the time portion from a datetime field in SQL Server?" Let's look at the two methods provided as options:

a) SELECT DATEADD(dd, DATEDIFF(dd, 0, GETDATE()), 0)

b) SELECT CAST(CONVERT(CHAR(11), GETDATE(), 113) AS DATETIME)

Both methods seem promising, but is there a difference in terms of performance? And are there even better methods out there? Let's find out!

Method a) using DATEADD and DATEDIFF

The first method uses the DATEADD and DATEDIFF functions. It calculates the number of days between the base date (0) and the current date using DATEDIFF, and then adds that number of days back to the base date using DATEADD. This effectively removes the time portion.

SELECT DATEADD(dd, DATEDIFF(dd, 0, GETDATE()), 0)

This method is concise and widely used. It provides an efficient way to remove the time part of a datetime field.

Method b) using CAST and CONVERT

The second method involves using the CAST and CONVERT functions. It first converts the datetime field to a specific format (char(11)) using CONVERT, and then casts it back to a datetime data type using CAST.

SELECT CAST(CONVERT(CHAR(11), GETDATE(), 113) AS DATETIME)

This method is also effective in removing the time portion. However, it involves an extra step of converting the field to a different format before casting it back to datetime.

Performance Considerations

Both methods seem fast and efficient for removing the time part of a datetime field. However, when dealing with hundreds-of-thousands or more rows, performance becomes a priority. It's essential to choose the method that provides the best performance in such scenarios.

To determine the performance, you can run both methods on your own database and compare the execution time.

Are There Even Better Methods?

While methods a) and b) are commonly used and provide efficient results, it's always good to explore other possibilities.

One alternative approach is to use the DATE data type introduced in SQL Server 2008. This data type stores only the date part, making it ideal for scenarios where the time component is not required. You can use CAST or CONVERT to convert the datetime field to the DATE data type.

SELECT CAST(GETDATE() AS DATE)

This method is straightforward and ensures that only the date part is retained.

Conclusion

Removing the time part from a datetime field in SQL Server is a common task. Both the DATEADD and DATEDIFF method (a) and the CAST and CONVERT method (b) provide efficient results. However, when it comes to performance, it's essential to benchmark them against your specific scenario.

Additionally, the newer DATE data type can be a viable solution in situations where the time component is not necessary.

Now that you have a better understanding of the best approach to removing the time part of a datetime field in SQL Server, why not give it a try in your own projects?

Let us know which method works best for you or if you have any other tips and tricks to share! Leave a comment below and let's continue the conversation.

Happy coding! ✨💻🚀