Exploring Date and Time Functions in PostgreSQL Database
Time is a fundamental aspect of our lives, and it is no different in the world of databases. The ability to manipulate and work with dates and times is an essential skill in database management.
PostgreSQL, an object-relational database, provides various functions for working with dates and times, including LOCALTIMESTAMP and CURRENT_TIMESTAMP. In this article, we will explore these functions and their differences in detail.
Getting current date and time in PostgreSQL database
PostgreSQL provides two functions that allow us to obtain the current date and time: LOCALTIMESTAMP and CURRENT_TIMESTAMP.
Using the LOCALTIMESTAMP function
The LOCALTIMESTAMP function returns the current date and time in the local time zone of the machine running PostgreSQL. The syntax of the function is as follows:
LOCALTIMESTAMP([precision])The precision argument specifies the maximum number of fractional seconds to be returned by the function.
It is an integer enclosed in brackets and ranges from 0 to 6, with 6 being the maximum number of fractional seconds. If the precision argument is not specified, the function returns the timestamp value with six fractional seconds by default.
Date and time format
The timestamp value returned by the LOCALTIMESTAMP function follows the format ‘YYYY-MM-DD hh:mm:ss.ssssss,’ where YYYY is the year, MM is the month, DD is the day, hh is the hour in 24-hour format, mm is the minute, ss is the second, and ssssss is the number of fractional seconds. For example, the following query returns the current date and time with a precision of three fractional seconds:
SELECT LOCALTIMESTAMP(3);It returns a value like ‘2021-11-23 15:44:27.378.’
Difference between LOCALTIMESTAMP and CURRENT_TIMESTAMP
LOCALTIMESTAMP and CURRENT_TIMESTAMP functions both return the current date and time, but there are some differences between them.
LOCALTIMESTAMP function
As mentioned earlier, the LOCALTIMESTAMP function returns the current date and time in the local time zone of the machine running PostgreSQL. This means that the timestamp value returned by the function may differ depending on the time zone of the machine, even if the server running PostgreSQL is in a different time zone.
CURRENT_TIMESTAMP function
The CURRENT_TIMESTAMP function also returns the current date and time. However, it returns the timestamp value adjusted to the time zone specified in the time zone offset parameter.
By default, the parameter is set to the time zone of the session. This means that the timestamp value returned by the function will be the same, regardless of the time zone of the machine running PostgreSQL.
Conclusion
In this article, we explored two functions for obtaining the current date and time in PostgreSQL database: LOCALTIMESTAMP and CURRENT_TIMESTAMP. We also discussed their differences and the format of the timestamp value returned by the LOCALTIMESTAMP function.
As you work with dates and times in PostgreSQL, these functions will be helpful tools in your database management toolkit. In this informative article, we explored the important topic of date and time functions in PostgreSQL databases.
We covered two primary functions for retrieving current date and time information: LOCALTIMESTAMP and CURRENT_TIMESTAMP. We discussed the syntax and formats of each function and highlighted the key differences between them.
As database management becomes increasingly important in today’s world, knowing how to manipulate and work with dates and times is a valuable skill. By understanding these essential functions in PostgreSQL, we can work with a wide range of date-related tasks more effectively to make sure our databases are running smoothly.