The SQL Server Equivalent of SYSDATE: GETDATE vs CURRENT_TIMESTAMP vs SYSDATETIME

Overview

When working with databases, it's important to know how to retrieve the current date and time in a consistent and accurate manner. In Oracle, the SYSdate function provides the current date and time set on the operating system on which the database resides. In SQL Server, similar functionalities exist, but with different methods. This article explores the SQL Server equivalents of SYSdate, specifically GETDATE, CURRENT_TIMESTAMP, and SYSDATETIME, and discusses their usage and benefits.

Understanding SYSDATE in Oracle

SYSdate in Oracle is a system function that returns the current date and time set for the operating system on which the database resides. It is particularly useful for applications that need to report the time within the context of the server's system clock.

The Equivalents in SQL Server

GETDATE

GETDATE is a SQL Server function that returns the current date and time as a datetime data type. This function is commonly used to get the current date and time within a SQL Server database. Here is how it can be used in T-SQL code:

SELECT GETDATE()

GETDATE returns a datetime value that includes both the date and time, such as 2021-07-21 01:36:34. It is widely used and compatible with standard SQL Server practices.

CURRENT_TIMESTAMP

CURRENT_TIMESTAMP is another function in SQL Server that provides the current date and time. It has been in use for a long time, and many database developers have relied on it for its reliability and simplicity. Its usage is straightforward:

SELECT CURRENT_TIMESTAMP

This function is also a datetime data type and returns the current date and time in the same format as GETDATE. It has been a reliable choice for many years, as mentioned by a long-time user who has been using it for over 15 years.

SYSDATETIME

SYSDATETIME is a system function in SQL Server that returns the current date and time with higher precision. It is more precise than GETDATE and CURRENT_TIMESTAMP as it returns the current date and time to the level of fractional seconds, and its resolution is better than the server’s implementation of SYSdate. This function is particularly useful in scenarios where higher precision is required. Here is an example of its usage:

SELECT SYSDATETIME()

SYSDATETIME returns a value with higher precision, such as 2023-10-01 12:34:56.78912. This function is especially beneficial in environments where milliseconds or even microseconds of precision are important.

SQL Server Databases and SYSDATETIME

For SQL Server databases, the SYSDATETIME function is a valuable tool for retrieving the current date and time with higher precision. However, it is important to note that this is a non-standard system object, which means it may not be available in all versions of SQL Server. For instance, in Informix, the equivalent query would be:

select sysdate from systables where tabid 1

or

select current year to fraction5 from systables where tabid 1

Both of these Informix queries retrieve the current date and time, but they may not offer the same level of precision as SYSDATETIME in SQL Server.

Conclusion

Choosing the right function to retrieve the current date and time in SQL Server depends on your specific needs and the precision required. If you need a simple and reliable solution, CURRENT_TIMESTAMP or GETDATE are excellent choices. For applications that require higher precision, SYSDATETIME is the way to go.