postgresql to_char time with code examples

PostgreSQL is a powerful open-source relational database management system used by many organizations worldwide to store and manage their data. It is known for its reliability, scalability, and support for various data types, including date and time. In this article, we will explore PostgreSQL's "to_char" function, which is used to convert a time value to a text representation.

The "to_char" function in PostgreSQL is a versatile function that can be used to convert various data types to text representation. It is particularly useful when working with dates and times, as it allows you to format the output to your liking. This function takes two arguments, the first being the value to be converted and the second being the format string. The format string is a pattern that specifies how the output will be formatted.

The following are some common date and time format patterns that can be used with the "to_char" function:

YYYY: Four-digit year
MM: Month (01-12)
DD: Day of the month (01-31)
HH: Two-digit hour (00-23)
MI: Two-digit minute (00-59)
SS: Two-digit second (00-59)
D: Day of the week (0-6)
PM: AM or PM

To use the "to_char" function with time values, we will start by creating a sample table in PostgreSQL:

CREATE TABLE test (id SERIAL, created_at TIMESTAMP);

INSERT INTO test (created_at)
VALUES
('2021-01-01 08:30:00'),
('2021-01-02 14:45:00'),
('2021-01-03 20:15:00');

In the above code, we created a table named "test" with two columns, "id" and "created_at." We also inserted some data into the table to work with for our examples.

Let's start by converting a time value to a text representation using the "to_char" function. In the following example, we will retrieve the "created_at" column from the "test" table and format it to display only the hour and minute values:

SELECT to_char(created_at, 'HH24:MI') FROM test;

Output:

08:30
14:45
20:15

In the above code, we used the "to_char" function to format the "created_at" column and display only the hour and minute values. The "HH24" pattern specifies a two-digit hour value in 24-hour format, while the "MI" pattern specifies a two-digit minute value.

Now let's say we want to display the time value in a different format, such as displaying the hour in AM/PM format. We can use the following code:

SELECT to_char(created_at, 'HH12:MI AM') FROM test;

Output:

08:30 AM
02:45 PM
08:15 PM

In the above code, we used the "HH12" pattern to display the hour in 12-hour format. The "AM" pattern specifies that the result is displayed in AM or PM format.

We can also use the "to_char" function to display the day of the week for a given date. The following example demonstrates how to do this:

SELECT to_char(created_at, 'Day') FROM test;

Output:

Friday
Saturday
Sunday

In the above code, we used the "Day" pattern to display the day of the week for each date in the "created_at" column.

Finally, we can use the "to_char" function to display the date and time together in a specific format. The following code example demonstrates how to do this:

SELECT to_char(created_at, 'MM/DD/YYYY HH:MI:SS') FROM test;

Output:

01/01/2021 08:30:00
01/02/2021 02:45:00
01/03/2021 08:15:00

In the above code, we used various patterns to format the date and time together. The "MM" pattern specifies the month value, "DD" specifies the day of the month, "YYYY" specifies the four-digit year, "HH" specifies the hour value, "MI" specifies the minute value, and "SS" specifies the second value.

Conclusion:

The "to_char" function in PostgreSQL is a powerful tool that allows you to convert time values to a text representation with customizable output formatting. It is particularly useful when working with date and time values and can produce output that can be easily read and analyzed by humans. With the various patterns available, you can format the output to meet your specific needs. The examples provided should give you a good starting point to work with this function in your own PostgreSQL database.

let me expand on some of the topics covered in the previous article.

Let's start with the "to_char" function and its usage with dates. The "to_char" function can be used to convert a date value to a text representation with a specific format by using various formatting patterns. Here are some examples:

SELECT to_char('2021-06-18', 'DD/MM/YYYY'); — Output: 18/06/2021
SELECT to_char('2021-06-18', 'Month DD, YYYY'); — Output: June 18, 2021
SELECT to_char('2021-06-18', 'YYYY-MM-DD'); — Output: 2021-06-18

In the first example, we used the "DD/MM/YYYY" pattern to display the date in day-month-year format. In the second example, we used the "Month DD, YYYY" pattern to display the date in the long format. In the third example, we used the "YYYY-MM-DD" pattern to display the date in the ISO 8601 format.

Moving on to timestamps, the "to_char" function can be used to convert a timestamp value to a text representation in a specific format by using various formatting patterns. Here are some examples:

SELECT to_char('2021-06-18 12:34:56', 'YYYY-MM-DD HH24:MI:SS'); — Output: 2021-06-18 12:34:56
SELECT to_char('2021-06-18 12:34:56', 'Mon DD, YYYY HH:MI:SS PM'); — Output: Jun 18, 2021 12:34:56 PM
SELECT to_char('2021-06-18 12:34:56', 'Day, Mon DD, YYYY'); — Output: Friday, Jun 18, 2021

In the first example, we used the "YYYY-MM-DD HH24:MI:SS" pattern to display the timestamp in the ISO 8601 format. In the second example, we used the "Mon DD, YYYY HH:MI:SS PM" pattern to display the timestamp in a long format with the PM indication. In the third example, we used the "Day, Mon DD, YYYY" pattern to display the timestamp in the long date format.

Another useful use case for the "to_char" function is to extract particular components of a date or timestamp value. For example, the "YEAR", "MONTH", "DAY", "HOUR", "MINUTE", and "SECOND" can be extracted using the corresponding formatting patterns. Here are some examples:

SELECT to_char('2021-06-18', 'YEAR'); — Output: 2021
SELECT to_char('2021-06-18', 'MONTH'); — Output: June
SELECT to_char('2021-06-18', 'DAY'); — Output: 18
SELECT to_char('2021-06-18 12:34:56', 'HOUR'); — Output: 12
SELECT to_char('2021-06-18 12:34:56', 'MINUTE'); — Output: 34
SELECT to_char('2021-06-18 12:34:56', 'SECOND'); — Output: 56

In the above examples, we used the "YEAR", "MONTH", "DAY", "HOUR", "MINUTE", and "SECOND" patterns to extract the corresponding components from the date or timestamp value.

To summarize, the "to_char" function is a powerful tool in PostgreSQL that allows you to format date and timestamp values easily. By using the various formatting patterns available, you can display the date and time values in different formats and extract particular components as needed. The examples provided should help you get started with using this function in your PostgreSQL database.

postgresql to_char time with code examples

Output:

Output:

Output:

Output:

Popular questions

Tag

Vikram Arsid

Leave a Reply Cancel reply

Output:

Output:

Output:

Output:

Popular questions

Tag

Vikram Arsid

Leave a Reply Cancel reply

Related Posts