PostgreSQL NOW() Function

Summary: in this tutorial, you will learn how to use the PostgreSQL NOW() function to get the current date and time with the time zone.

Introduction to PostgreSQL NOW() function

The NOW() function returns the current date and time with the time zone of the database server.

Here’s the basic syntax of the NOW() function:

NOW()

The NOW() function doesn’t require any argument. Its return type is the timestamp with time zone. For example:

SELECT NOW();

Output:

now
-------------------------------
 2024-01-26 18:14:09.101641-08
(1 row)

Note that the NOW() function returns the current date and time based on the database server’s time zone setting.

For example, if you change the timezone to ‘Africa/Cairo’ and get the current date and time:

SET TIMEZONE='Africa/Cairo';
SELECT NOW();

Output:

now
-------------------------------
 2024-01-27 04:15:20.112974+02
(1 row)

The output indicates that the value returned by the NOW() function is adjusted to the new timezone.

Note that to get a complete list of time zones, you can query from the pg_timezone_names:

SELECT * FROM pg_timezone_names;

Partial output:

name               | abbrev | utc_offset | is_dst
----------------------------------+--------+------------+--------
 Africa/Abidjan                   | GMT    | 00:00:00   | f
 Africa/Accra                     | GMT    | 00:00:00   | f
 Africa/Addis_Ababa               | EAT    | 03:00:00   | f
...

If you want to get the current date and time without a timezone, you can cast it explicitly as follows:

SELECT NOW()::timestamp;

Output:

now
----------------------------
 2017-03-17 18:37:29.229991
(1 row)

You can use the common date and time operators for the NOW() function. For example, to get 1 hour from now:

an_hour_later
------------------------------
 2024-01-27 05:16:17.15237+02
(1 row)

To get this time tomorrow, you add 1 day to the current time:

SELECT (NOW() + interval '1 day') AS this_time_tomorrow;

Output:

this_time_tomorrow
-------------------------------
 2024-01-28 04:16:28.308575+02
(1 row)

To get 2 hours 30 minutes ago, you use the minus (-) operator as follows:

SELECT now() - interval '2 hours 30 minutes' AS two_hour_30_min_go;

Output:

two_hour_30_min_go
-------------------------------
 2024-01-27 01:47:18.246763+02
(1 row)

PostgreSQL NOW() related functions

Besides the NOW() function, you can use the CURRENT_TIME or CURRENT_TIMESTAMP to get the current date and time with the timezone:

SELECT CURRENT_TIME, CURRENT_TIMESTAMP;

Output:

current_time    |       current_timestamp
--------------------+-------------------------------
 04:17:46.412062+02 | 2024-01-27 04:17:46.412062+02
(1 row)

To get the current date and time without a timezone, you use the LOCALTIME and LOCALTIMESTAMP functions.

SELECT LOCALTIME, LOCALTIMESTAMP;

Output:

time       |         timestamp
-----------------+----------------------------
 19:13:41.423371 | 2017-03-17 19:13:41.423371
(1 row)

Notice that NOW() and its related functions return the start time of the current transaction. In other words, the return values of the function calls are the same within a transaction.

The following example illustrates the concept:

postgres=# BEGIN;
BEGIN
postgres=# SELECT now();
              now
-------------------------------
 2017-03-17 19:21:43.049715-07
(1 row)


postgres=# SELECT pg_sleep(3);
 pg_sleep
----------

(1 row)


postgres=# SELECT now();
              now
-------------------------------
 2017-03-17 19:21:43.049715-07
(1 row)


postgres=# COMMIT;
COMMIT

In this example, we called the NOW() function within a transaction and its return values do not change through the transaction.

Note that the pg_sleep() function pauses the current session’s process sleep for a specified of seconds.

If you want to get the current date and time that does advance during the transaction, you can use the TIMEOFDAY() function. Consider the following example:

SELECT
    TIMEOFDAY(),
    pg_sleep(5),
    TIMEOFDAY();

Output:

timeofday              | pg_sleep |              timeofday
-------------------------------------+----------+-------------------------------------
 Sat Jan 27 04:19:08.650831 2024 EET |          | Sat Jan 27 04:19:13.655833 2024 EET
(1 row)

After pausing 5 seconds, the current date and time increased.

PostgreSQL NOW() function as default values

You can use the NOW() function as the default value for a column of a table. For example:

First, create a new table named posts with the created_at column that has a default value provided by the NOW() function:

CREATE TABLE posts (
     id         SERIAL PRIMARY KEY,
     title      VARCHAR NOT NULL,
     created_at TIMESTAMPTZ DEFAULT Now()
);

Second, insert a new row into the posts table:

INSERT INTO posts (title)
VALUES     ('PostgreSQL NOW function');

Third, query data from the posts table:

SELECT * FROM posts;

Output:

id |          title          |          created_at
----+-------------------------+-------------------------------
  1 | PostgreSQL NOW function | 2024-01-27 04:20:11.286958+02
(1 row)

Even though we did not provide the value for the created_at column, the statement used the value returned by the NOW() function for that column.

Summary

• Use the PostgreSQL NOW() function to get the current date and time with the timezone.