How to Convert Timestamp to Date in PostgreSQL

Date and timestamps are useful for data analysis and storage to see when an event actually occurred. For instance, if you have a buy/sell order, monthly or quarterly revenue, etc. 

PostgreSQL includes a number of functions for working with dates. These functions can be used to convert a particular string to a date, or simply to get the current system date. However, you may want to provide a timestamp and convert it to date. To streamline this, PostgreSQL provides several functions that allow you to convert any given timestamp to date in an efficient manner.

This article will walk you through some of the most efficient methods to convert timestamp to date PostgreSQL.

Table of Contents

• What is PostgreSQL?
• What is Timestamp?
• Methods to Convert Timestamp to Date PostgreSQL
• Conclusion

What is PostgreSQL?

PostgreSQL is an open-source, high-performance relational database that supports both SQL (relational) and JSON (non-relational) querying. It’s a very dependable database management system that owes its high levels of robustness, integrity, and correctness to more than two decades of community labor. PostgreSQL is used as the primary data storage or data warehouse in many internet, mobile, geospatial, and analytics applications.

PostgreSQL’s source code is publicly available under an open-source license, letting you to use, edit, and adapt it as you see fit. PostgreSQL’s dedicated community of contributors and aficionados discovers bugs and patches on a regular basis, contributing to the general security of the database system.

What is Timestamp?

A timestamp is a piece of temporal information about an event that a computer records and stores as a log or metadata. Depending on the demands of the user or the capabilities of the process providing the timestamp, every event or activity might have a timestamp recorded.

The term “timestamp” refers to the combination of date and time. This number might be the current date and time, or any other random day and time.

Timestamps are required for most computer-related tasks, particularly for synchronization. For example, timestamps on backup files are required so that the backup mechanism can tell the difference between the backup file and the current file, such as whether it has been updated or not as indicated by the date-modified timestamp.

Methods to Convert Timestamp to Date PostgreSQL

Method 1 to Convert Timestamp to Date PostgreSQL: Using PostgreSQL’s Now Function

PostgreSQL’s “Now” function may be used to obtain the present timestamp, i.e. the current date and time. It may be used upon the current timestamp to convert timestamp to date PostgreSQL when paired with the “date” keyword and the “::” operator. To see this, all you have to do is execute the following query:

# SELECT NOW()::date;

Finally, as illustrated in the snapshot below, the “SELECT” command will display the following results on the console:

Method 2 to Convert Timestamp to Date PostgreSQL: Using the To_Char Function with the Now Function in PostgreSQL

The current date is derived from the current timestamp using the PostgreSQL query representation given above. However, the date is always displayed in the yyyy-mm-dd format in the output by default. If you wish to change the output format, i.e., retrieve the date from the timestamp in a format different than the usual one, use the following query:

The same “Now” function is used in this query to extract the current timestamp; however, the “DATE” keyword is followed by a custom date format, i.e., dd-mm-yyyy, which differs from the default date format. You may also use any other date format you like here. All of these inputs are eventually sent on to the “TO_CHAR” function, which will execute the final transformation of the current date into the format specified in this query, and all of this will be shown on the console using the “SELECT” command, as shown below:

Method 3 to Convert Timestamp to Date PostgreSQL: Using PostgreSQL’s Extract Function

Instead of extracting the entire date from the given timestamp, you may only wish to display a certain component of the date, such as the year, month, or day. In such a scenario, you must run a different PostgreSQL query, which is as follows:

# SELECT EXTRACT(MONTH FROM TIMESTAMP ‘2021-03-22 10:25:15’) as month;

The month was to be extracted from the timestamp in this query. As a result, we sent the “MONTH” keyword to the “Extract” function as an input, followed by the “TIMESTAMP” keyword, which is followed by a random timestamp (you can also use the current timestamp over here if you want). Lastly, the word “as month” will simply name our output for greater clarity. If you like, you may skip this sentence. As illustrated in the snapshot below, the “SELECT” statement will be in charge of presenting the desired output on the console. 

Similarly, you may extract the year or day from the supplied timestamp by using PostgreSQL’s “Extract” function and replacing the “MONTH” keyword in the parameters with “YEAR” or “DAY,” respectively.

Method 4 to Convert Timestamp to Date PostgreSQL: Using PostgreSQL’s Date Part Function

The PostgreSQL “Date Part” function may also be used to retrieve the day, month, and year, i.e. the date, from the provided timestamp. You must run the following PostgreSQL query to make the “Date Part” function complete this task:

This query will use PostgreSQL’s “Date Part” function three times to extract the day, month, and year from the provided timestamp one by one. These three entities cannot be retrieved at the same time using the “Date Part” function; instead, you must execute this function three times inside the same query, which is why it is a very inefficient method of extracting the date from the provided timestamp. You may, however, modify the output format in which you will receive the date after executing this query by just changing the order of this query.

Conclusion

This article defines a timestamp and why it is necessary to convert timestamp to date PostgreSQL in the first place. After that, it covers the techniques to convert timestamp to date PostgreSQL one by one. When it comes to efficiency, the first two techniques are the most effective in achieving this aim. In terms of the third approach, you can only extract a single entity of date from the specified timestamp at a time, such as a year, month, or day. Concerning the fourth approach, because it performs the same operation three times, its computing cost is large, making it less efficient. However, these methods may be used to obtain the date from a timestamp in PostgreSQL.

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