EDUCBA

Home » Data Science » Data Science Tutorials » PostgreSQL Tutorial » PostgreSQL EXTRACT()

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:

Start Your Free Data Science Course

Hadoop, Data Science, Statistics & others

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:

UNIT TIMESTAMP INTERVAL
CENTURY A century The century number
DAY A day of the given month

Numbered like (1-31)

 The day number
DECADE a year which is divided by ten Similar to TIMESTAMP
DOW Weekday (0) Sunday to (6) Saturday NIL
DOY A day of the given year numbered like

(1 – 366)

 NIL
EPOCH A second number from ‘1970-01-01 00:00:00’ UTC The second number
HOUR The hour numbered like (0-23) The hour number
ISODOW A day of the given week which is defined on ISO 8601 Monday to Sunday NIL
ISOYEAR ISO 8601 week number of year NIL
MICROSECONDS seconds with fractional parts, which is multiplied with ‘1000000.’ Similar to TIMESTAMP
MILLENNIUM The millennium The millennium number
MILLISECONDS seconds with fractional parts, which is multiplied with ‘1000.’ Similar to TIMESTAMP
MINUTE A minute numbered like (0-59) The minute number
MONTH A Month numbered like 1-12 The month number which is modulo by (0-11)
QUARTER the quarter of the given year The quarter number
SECOND A second The second number
TIMEZONE It is in seconds NIL
TIMEZONE_HOUR The time zone’s hour field. NIL
TIMEZONE_MINUTE The time zone’s minute field. NIL
WEEK The week of the giver year as per the ISO 8601 NIL
YEAR A year

 

 

 Similar to TIMESTAMP

 

 

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.

PostgreSQL EXTRACT()-1.1

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');

PostgreSQL EXTRACT()-1.2

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

PostgreSQL EXTRACT()-1.3

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

PostgreSQL EXTRACT()-1.4

  • Consider the following examples to extract timestamp values.

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

 PostgreSQL EXTRACT()-1.5

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

PostgreSQL EXTRACT()-1.6

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

PostgreSQL EXTRACT()-1.7

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

PostgreSQL EXTRACT()-1.8

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

Output-1.9

  • Consider the following examples to extract time values.

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

Output-1.10

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

Output-1.11

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

Output-1.12

  • Consider the following examples to extract interval values.

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

Output-1.13

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

Output-1.14

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
0 Shares
Share
Tweet
Share