PostgreSQL CURRENT_TIMESTAMP Function

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

Introduction to PostgreSQL CURRENT_TIMESTAMP() function

The CURRENT_TIMESTAMP function returns the current date and time with the timezone.

Here’s the basic syntax of the PostgreSQL CURRENT_TIMESTAMP() function:

CURRENT_TIMESTAMP(precision)

The PostgreSQL CURRENT_TIMESTAMP() function accepts one optional argument:

precision: specifies the number of digits in the fractional seconds precision in the second field of the result.

If you omit the precision argument, the CURRENT_TIMESTAMP() function will return a TIMESTAMP with a timezone that includes the full fractional seconds precision available.

The CURRENT_TIMESTAMP() function returns a TIMESTAMP WITH TIME ZONE representing the date and time at which the transaction started.

PostgreSQL CURRENT_TIMESTAMP function examples

Let’s explore some examples of using the CURRENT_TIMESTSAMP function.

1) Basic CURRENT_TIMESTSAMP function example

The following example shows how to use the CURRENT_TIMESTAMP() function to get the current date and time:

SELECT CURRENT_TIMESTAMP;

The result is:

now
-------------------------------
 2017-08-15 21:05:15.723336-07
(1 row)

Internally, the CURRENT_TIMESTAMP() is implemented with the NOW() function, therefore, the column alias is NOW.

Like the NOW() function, the CURRENT_TIMESTAMP() function can be used as the default value of a timestamp column.

2) Using the PostgreSQL CURRENT_TIMESTSAMP function as the default value of a column

First, create a table called note:

CREATE TABLE note (
    id SERIAL PRIMARY KEY,
    message VARCHAR(255) NOT NULL,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP
);

The default value of the created_at column is provided by the result of the CURRENT_TIMESTAMP() function.

Second, insert a new row into the note table:

INSERT INTO note(message)
VALUES('Testing current_timestamp function');

In this statement, we don’t specify the value of the created_at column. Therefore, it takes the result of the CURRENT_TIMESTAMP at which the transaction started.

Third, verify the insert:

SELECT * FROM note;

The following picture illustrates the result:

id |              message               |          created_at
----+------------------------------------+-------------------------------
  1 | Testing current_timestamp function | 2024-01-26 15:47:44.199212-07
(1 row)

The output indicates that the created_at column is populated by the date and time at which the statement was executed.

In PostgreSQL, the TRANSACTION_TIMESTAMP() function is synonymous with the CURRENT_TIMESTAMP function. However, the name of the function TRANSACTION_TIMESTAMP more explicitly conveys the meaning of the return value.

Summary

Use the PostgreSQL CURRENT_TIMESTAMP() to get the date and time at which the transaction starts.