PostgreSQL EXTRACT()

Definition of PostgreSQL EXTRACT()

PostgreSQL extract function() is used to fetch the subfields from a date/time value field, like as in an hour or year, or day. The input field should be a date-time field. The input field is a string of date-time value or interval or timestamp from which we extract the fields like the second, minute, hour, date, etc. There are various units supported by PostgreSQL in which we can extract the input date-time source string. As a return result, the PostgreSQL EXTRACT() function gives a double-precision value.

Syntax:

Consider the following syntax of the PostgreSQL EXTRACT() function:

extract(unit from timestamp)
or
extract(unit from interval)

Explanation:

• Timestamp or Interval: It is the input source string from which the unit is gets extracted.
• Unit: This defined the type of the unit to extract like a minute, hour, day, month, and so on.

Consider the following table to understand the possible values of the unit:

How does PostgreSQL EXTRACT() Function Work?

Consider the following pictorial representation for understanding the working of the extract function; as per the unit specified in the EXTRACT syntax, the PostgreSQL EXTRACT function extracts the unit from the input and returns that value.

Implementing EXTRACT() Function in PostgreSQL

Let’s consider the following examples for understanding the PostgreSQL extract function examples.

• Consider the following examples to extract date values:

SELECT extract(day from date '2020-04-03');

SELECT extract(month from date '2020-04-03') AS MONTH;

SELECT extract(year from date '2020-04-03') AS year;

• Consider the following examples to extract timestamp values.

SELECT extract(day from timestamp '2020-04-03 09:57:10');

SELECT extract(month from timestamp '2020-04-03 09:57:10');

SELECT extract(minute from timestamp '2020-04-03 09:57:10');

SELECT extract(second from timestamp '2020-04-03 09:57:10');

SELECT extract(hour from timestamp '2020-04-03 09:57:10');

• Consider the following examples to extract time values.

SELECT extract(minute from time '09:57:10');

SELECT extract(second from time '09:57:10');

SELECT extract(milliseconds from time '09:57:10.5');

• Consider the following examples to extract interval values.

SELECT extract(day from interval '4 days 4 hours');

SELECT extract(hour from interval '4 days 4 hours');

Advantages of using EXTRACT() Function in PostgreSQL

• We can extract the units like a day, month, hour, minute and many more from the source string by using the EXTRACT function.
• The PostgreSQL EXTRACT() function gives a double-precision value.
• The unit defined to fetch the result is human readable.
• We can extract the input source of type timestamp, interval, and date-time, etc.

Conclusion

We hope from the above article you have understood how to use the PostgreSQL EXTRACT() function and how the PostgreSQL EXTRACT() function works. Also, we have added several examples of the PostgreSQL EXTRACT() function to understand it in detail.

Recommended Articles

This is a guide to PostgreSQL EXTRACT(). Here we also discuss the Introduction and how does PostgreSQL extract() function works? Along with different examples and its code implementation. You may also have a look at the following articles to learn more –

1. PostgreSQL Administration
2. PostgreSQL LAG()
3. PostgreSQL LIMIT
4. PostgreSQL Alias
5. PostgreSQL SERIAL | Examples