In this PostgreSQL tutorial, I will show you the Postgres timestamp comparison to compare the timestamp value.
I will explain to you “What is timestamp?” and also some operators and functions that you can use to compare timestamp values. Additionally, you will learn how to compare timestamps using different real-world examples with different operators and functions.
Postgres Timestamp Comparison
Timestamps in the PostgreSQL database represent the date and time, It play a very important role in database management when you need to record any changes to the data, perform time-based analysis or track some kind of events.
PostgreSQL provide a data type called timestamp to store the timestamps value in the column of the table which is the combination of date and time. Also, PostgreSQL provides different kinds of operators or functions to compare the timestamp value.
Operators and function for comparing timestamp is given below in the table:
|Operators Or Functions
|To check if a timestamp is less than the other
|To check if a timestamp is less than other
|To check if a timestamp is greater than or equal to another
|To check if a timestamp is greater than the other
|To check if two timestamps are equal
|To check if two timestamps are not equal
|It is an interval operator to find the difference between timestamps such as timestamp_1 – timestamp2.
|It is a function to computes the difference between timestamp and give the result as an interval
|To find the range of timestamp
Let’s see with a practical example how to compare timestamps using the operators and functions.
Suppose you are a frontend and backend developer and developing the scheduling app, you have a task to write a query that shows if any event is in the future or has passed already. The events table is shown below.
Now you use the below query to see if the event is coming or has passed already.
SELECT event_name, event_time
WHERE event_time > CURRENT_TIMESTAMP;
The output of the above query shows the upcoming event name with timestamp(date and timing). At line 3 within the WHERE clause greater than (>) operator is used to compare the timestamp value within column event_time with the CURRENT_TIMESTAMP (this reterive the current date and time).
Take one more example, you work at a company that has a social site and you have the task of tracking the last changes to the user profiles. Actually, you need to find the user who has updated their profile in the last six months. The user_profiles table is shown below.
Use the below query to find the changes to the user profiles.
SELECT username, user_id, last_updated
WHERE last_updated < CURRENT_TIMESTAMP - INTERVAL '6 months';
The above query shows that the user Sebstian, Ezra and Leo has updated their profile in the last six months.
Now look at line number 3 which compares the timestamp value of column last_updated with six months ago from the current time, and for comparing timestamps less than (<) operator is used.
The statement CURRENT_TIMESTAMP – INTERVAL ‘6 months’ represents the six months from the current date and time. This statement subtracts 6 months from the current timestamp and returns a new timestamp that represents the point in time exactly 6 months ago from the current time
Postgres Timestamp Comparison Using Age()
You are a database developer of an E-commerce website and you have to create a query that can return the age of the products in inventory to prioritize restocking, so you will use the function age() to compute the age of the products based on the given manufacturing date of the products.
The products table is shown below.
Use the below query to compute the age of the products.
SELECT product_name, manufacturing_date, age(manufacturing_date)
In the above query, the function age() computes the age of the product based on the column manufacturing_date as you can see in the output.
Postgres Timestamp Comparison Using Between
Suppose you manage a retail store and you have a task to analyze the products that were restocked between July 1, 2023 and August 31, 2023. You have access to the table inventory which is shown below.
Now use the below query to analyze the product between 1 July and August 31, 2023.
SELECT restock_date, product_name, restock_quantity
WHERE restock_date BETWEEN '2023-07-01' AND '2023-08-31';
The above query returns the products that were restocked between 1 July and 31st August 2023 which you can see in the above output.
The BETWEEN is used with AND to compare the timestamp value of column restock_date. There are other operators or functions that you can use to compare timestamps according to your needs.
In this PostgreSQL tutorial, you have covered how to compare timestamps in PostgreSQL with different operators and functions. Additionally, you learned how to use some of the operators and functions with real-world examples to compare timestamps.
You may also read:
- How to use PostgreSQL current_timestamp
- Postgresql difference between two timestamps
- PostgreSQL TO_TIMESTAMP function + Examples
I am Bijay having more than 15 years of experience in the Software Industry. During this time, I have worked on MariaDB and used it in a lot of projects. Most of our readers are from the United States, Canada, United Kingdom, Australia, New Zealand, etc.
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