CREATE OR REPLACE FUNCTION round_time (timestamp with time zone) RETURNS timestamp with time zone AS $$ SELECT date_trunc ('hour', $ 1) + interval '5 min' * round (date_part ('minute', $ 1) / 5. ) Example of grouping sales from orders by month: select SUM(amount) as sales, date_trunc('month', created_at) as date from orders group by. The SELECT statement below extracts the quarter each date_renting falls in. 1 starts: 9. The DATE type in PostgreSQL can store a date without an associated time value: PostgreSQL uses 4 bytes to store a date value. These SQL-standard functions all return values based on the start time of the current transaction:DATE_TRUNC. In the docs I could only find a way to create a date from a string, e. ). For formatting functions, refer to Section 9. For formatting functions, refer to Section 9. Share. 1. answered Dec 28, 2011 at 13:33. date_trunc (field, source [, time_zone ]) source is a value expression of type timestamp, timestamp with time zone, or interval. The range of values for date values in PostgreSQL is 4713 BC to 5874897 AD. PostgreSQL - DATE/TIME Functions and Operators. From the documentation: date_part (): The date_part function is modeled on the traditional Ingres equivalent to the SQL-standard function extract: 2. Table 9. Both solutions include the last day of the previous month and also include all of "today". Note: This shows two methods of doing the conversion, the first is the standard method. Here's the correct way to do it, with date_trunc: SELECT date_trunc ('month', txn_date) AS txn_month, sum (amount) as monthly_sum FROM yourtable GROUP BY txn_month. The Oracle code that I posted returns april 22, so I need postgres to do the same. PostgreSQL DATE_PART examples. However, with Postgres 14, the EXTRACT function now returns a numeric type instead of an 8-byte float. So first the timestamp is converted to a date (that does not have a time), and then the time value is added to that, which yields a timestamp. A primer on working with time in Postgres. Share. DATETIME_TRUNC(datetime_expression, part) Example: DATETIME_TRUNC('2019-04-01 11:55:00', HOUR) Output: 2019-04-01 11:00:00. created), 'YYYY-MM-DD')) GROUP BY d. SELECT EXTRACT (QUARTER FROM TIMESTAMP '2011-11-22 13:30:15') So the resultant quarter will be EXTRACT QUARTER from Timestamp in column of Postgresql table:. (In our example, we used month precision. , week, month, and year. orafce should be among them. Here's the best GROUP BY query I have so far: SELECT d. 2. Nice. I am trying to use the Date_Trunc for MONTH function in a SQL statement but somehow it is not working for me. Follow answered Jun 19, 2013 at 9:23. Say,. PostGreSQL : date_trunc() returns timestamp with timezone when used on date. Postgres date_trunc quarter with a custom start month. Data Type Formatting Functions. timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00'. Add a comment. SELECT date, region, revenue FROM sales WHERE date = (SELECT MAX(date) from sales WHERE date between date_trunc('quarter', CURRENT_DATE)::date -. 'QUARTER' First day of its quarter. The precision parameter is case-insensitive. SELECT date_trunc. PostgreSQL Date Functions Manipulation. PostgreSQL – DATE_TRUNC Function. 27 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. Share. One of these functions is DATE_TRUNC. 0. See the example below to see how you can aggregate by MONTH: SELECT SUM(number) AS total, DATE_TRUNC (date, MONTH) AS month FROM ( SELECT CAST('2021-02-04' AS DATE) AS date, 3 AS number UNION ALL ( SELECT. 9. Note: All the date field parts other than the targeted. SELECT EXTRACT (YEAR FROM TIMESTAMP '2001-02-16 20:38:40'); Result: 2001. A column of data type TIMESTAMP or an expression that implicitly evaluates to a TIMESTAMP type. For. EXTRACT, date_part EXTRACT (field FROM source) The extract function retrieves subfields such as year or hour from date/time values. 1994-10-27. It’s possible in Postgres to truncate or round a given timestamp to some given level of precision. Table 9. - The value for the “field” argument must be valid. The date_trunc function allows values that aren’t obvious parts of timestamps, like week and quarter. Column [source] ¶ Returns timestamp truncated to the unit specified by the format. 963179 secs juin 2, 2022, 12:00 AM | 0 years 0 mons 0 days 0 hours 2 mi. select date_trunc ('minute', created_at), -- or hour, day, week, month, year count(1) from users group by 1. For more information, see TRUNC function. SELECT SUM(orders. You can then add more conditions to the CASE/WHEN for additional quarters. Table 9-28 shows the available functions for date/time value processing, with details appearing in the following subsections. 1. 1. Well, In postgres, it seems there's no such function equivalent to LAST_DAY() available in oracle. Table 9. If you're certain that column should always store only the first of a month, you should also use a CHECK constraint. 9. Improve this answer. 11. Postgres quarter function. The quarter of the year (1 - 4) that the date is in. 2014-05-09 16:03:51 will be returned as 2014-05-01 00:00:00. 1 Answer. SELECT EXTRACT(QUARTER FROM TIMESTAMP '2001-02-16 20:38:40'); Result: 1. Does PostgreSQL have such a built-in function?Functions and Operators. If you want both quarter and year you can use date_trunc: SELECT date_trunc('quarter', published_date) AS quarter This gives the date rounded to the. The quarter of the year (1–4) that the date is in. SQL Server: Date truncation for custom time periods. Note that the 'first day of the week' is not uniform across databases. TRUNC(timestamp) Arguments. Finally, it returns the truncated part with a specific precision level. GROUP BY 1. source must be a value expression of type timestamp, time, or interval. Basically, there are two parameters we. create index on test (date_trunc('month', foo::timestamp )); the problem with foo at time zone 'GMT' is that the expression foo at time zone 'GMT' is not itself immutable. 0) $$ LANGUAGE sql;The PostgreSQL DATE_TRUNC function is used to truncate the date and time values to a specific precision (into a whole value), such as 'year', 'month', 'day', 'hour', 'minute', or 'second', in a string format. You can truncate the current date to its quarter, then remove 1 day from that (and potentially cast back to date): -- You really only need the last column, the other two just show the different steps in the process SELECT DATE_TRUNC ('quarter', CURRENT_DATE) , DATE_TRUNC ('quarter', CURRENT_DATE) - '1 day'::INTERVAL. The following table lists the behaviors of the basic arithmetic operators −. SELECT date_trunc ('month', l_date) month FROM this_table GROUP BY month. Assuming data type timestamp. , “Year” in the above example) to their initials. date_trunc () is a system function for truncating a timestamp or interval to a specified unit. I need to find the value of the previous quarter for a particular given date. if you want timestamp instead of timestamptz cast the date to timestamp first. Go forth and write fearless (read-only) SQL!only date_trunc(text,interval) and date_trunc(text,timestamp) are immutable. For formatting functions, refer to Section 9. config. This function can also truncate a number. trunc (teste TIMESTAMP WITHOUT TIME ZONE). SELECT date_trunc('week', date::date) AS "weekly", COUNT(DISTINCT(date)) AS "working_days" FROM "public". ). It may be ugly, but it sure works! Here is my query: SELECT Date, interval (trunc (date_part ('epoch', time)/1800) * 1800) AS HALFHOUR, SUM (Data) FROM Table GROUP BY Date, HALFHOUR; This seems to work great, and I don't see any performance hit either. For formatting functions, refer to Section 9. Learn more about Teamsdate_trunc('hour', timestamp '2001-02-16 20:38:40') 2001-02-16 20:00:00: extract. I am using PostgreSQL 9. Remove the longest string that contains specified characters from the right of the input string. Also, we can calculate time intervals using these functions that will help us. Get the number of remaining days after excluding date ranges in a table. It's best explained by example: date_trunc('hour',TIMESTAMP '2001-02. ) This function takes two arguments. date; The results:By implementing the feature above, we are going to learn the following date functions in PostgreSQL: Truncate date with date_trunc; Extract date parts, such as weekday, month and year with date_part. date_trunc can be really helpful if you want to roll up time fields and count by day or month. Delaying Execution. (Expressions of type date will be cast to timestamp and can therefore be used as well. 9. Almost as it can't take any interval with units of months or more (due to varying duration). SELECT EXTRACT ('quarter' FROM now()); date_part-----1 #2. So if I run the SQL now, it should give me sep 30 2012. 5. Also, I'm leaving out '10:00'. 2k 3 64 88. , 2000-12-31. Takes two arguments, the date to truncate and the unit of. LOCALTIME(precision) Arguments. Delaying Execution. For example, because the common calendar starts from the year 1, the first decade (decade 1) is 0001-01-01 through 0009-12-31, and the second decade (decade 2) is 0010-01-01 through 0019-12-31. My current work around is to map date_trunc as a function and explicitly call it but it seems odd to have to do that. date_trunc ( field, source [, time_zone ]) source is a value expression of type timestamp, timestamp with time zone, or interval. 2017-05-14 20:38:40. To store date values, you use the PostgreSQL DATE data type. They both do very different things. try this : SELECT datepart (quarter,transaction_date), count (distinct UNIQUE_ID) as cnt FROM panel WHERE (some criteria = 'x') GROUP BY datepart (quarter,p. Adding a month gives you the first of the following month. PostgreSQL Date Functions (and 7 Ways to Use Them in Business Analysis). +01 +02 etc depends on your time locale's daylight saving rules. In order to group our orders by month, in PostgreSQL we'll use the date_trunc built-in function. If, however, the number of different days is significantly lower, the problem is that PostgreSQL has no way to estimate the distribution of date_trunc's results unless you create an index:. Args:. 6. 19, earlier I have made the following Query. 1. md","contentType":"file"},{"name":"Script-CREATE-TABLE-dim_date. Finding the last date of the previous quarter from current date in PostgreSQL Ask Question Asked 477 times 0 For example: If my current date is 2022. or you can create your own. 662522'); You can also use the date_trunc () function truncate a value of type interval, for. date_trunc can be really helpful if you want to roll up time fields and count by day or month. 9. What I need is to "round down" the month to day one, and I. Group by Year. 0. RETURN DATE_PART('day', (DATE_TRUNC('week', end_t) - DATE_TRUNC('week',. 9. ) field is an identifier or string that selects what field to extract. To return. Table 9. date, q2. Thank you very much for your. date_created >= { {date_range_start}} and l. Date Dimension for Postgres. Teams. 8. Table 9. You can truncate the current date to its quarter, then remove 1 day from that (and potentially cast back to date): -- You really only need the last column, the other two just show the different steps in the process SELECT DATE_TRUNC ('quarter', CURRENT_DATE) , DATE_TRUNC ('quarter',. In Postgres, you can use the EXTRACT(), DATE_TRUNC(), and DATE_PART() function to extract the month from a date field and then use the GROUP. Jimmy. Code: SELECT DATE_TRUNC('day', day_date), COUNT(1) AS count FROM day_test GROUP BY DATE_TRUNC('day', day_date); Output:Using the DATE_TRUNC function, you can truncate to the weeks, months, years, or other date parts for a date or time field. 必需的。 它是一个字符串表示要截取到部分。您可以是使用以下值： microseconds; milliseconds; second; minute; hourBasically this expression gives you the last day of the current quarter (provided that you remove the last closing parenthese, which otherwise is a syntax error). There is no function you want, but as said in postgresql wiki you can define function for youself: CREATE OR REPLACE FUNCTION round_time_10m (TIMESTAMP WITH TIME ZONE) RETURNS TIMESTAMP WITH TIME ZONE AS $$ SELECT date_trunc ('hour', $1) + INTERVAL '10 min' * ROUND (date_part ('minute', $1) / 10. SELECT TRUNC(datevalue, 'MONTH') FROM datelist; Result: 01/MAR/22. 2017) YEAROFWEEKISO. , ‘year’, ‘quarter’, ‘month’, ‘day’, ‘hour’, ‘minute’, ‘second’, etc. so you can distinct it first in the table then do the count. with ats (old_tz) as (select now() ) select old_tz, '2015-12-31'::timestamptz + (old_tz - date_trunc('day', old_tz)) new_tz from ats; OOPS. RPAD (‘ABC’, 6, ‘xo’) ‘ABCxox’. sales FROM Q1 UNION ALL SELECT q2. This can be generalized to any type of grouping. Common culprits are: > > *) CASE expressions > *) COALESCE > *) casts > *) simple tranformational expressions > *) predicate string concatenation *) time/date functions, ie WHERE date_trunc( 'quarter', some_timestamp ) = '2014-1-1' Though, in this case it's probably much better to teach the parser how to turn that into a range expression. PostgreSQL's date_trunc in mySQL Ask Question Asked 12 years, 7 months ago Modified 10 months ago Viewed 43k times 26 Recently, I have been getting familiar. millenium. Special calculation is needed for week/quarter. These SQL-standard functions all return values based on the start time of the current. 9999999 which your desired condition would not include). Table 9. In PostgreSQL, DATE_TRUNC Function is used to truncate a timestamp type or interval type with specific and high level of precision. in general, in group by queries, does it matter whether using - functions on the date - a day table that has extraction pre-calculated. So, this new function, date_bin, but it takes (almost) any interval as base for truncation. Current Date/Time. You can also use add_months to subtract months by specifying a negative integer. PostgreSQL provides a number of functions that return values related to the current date and time. 10. Date Dimension for Postgres. 摘要：本教程向您展示如何使用 PostgreSQL 的date_trunc()函数，将时间戳或间隔值截断到指定的精度级别。 PostgreSQL date_trunc 函数简介. This macro splits a string of text using the supplied delimiter and returns the. 1 starts: 9. 9. AT TIME ZONE. 1. 9. The easiest thing to do is to pass in dates for the start and end of the month: select * from generate_series ( '2018-08-01' ::timestamptz, '2018-08-31' ::timestamptz, '1 day' ); That works as expected, but it's cumbersome. Neither of those expressions will make use of an index on created - you would need to create an expression based index with the expression used. date_trunc always returns a timestamp, not a date. 'QUARTER': truncate to the first date of the quarter. In PostgreSQL, the DATE_TRUNC () function trims unnecessary values from the date and time and returns a result with specific precision. These SQL-standard functions all return. AT TIME ZONE. Sorted by: 3. Ordering by month & year numbers in Postgres. One possibility: select year * '1 year'::interval + '0000-01-01'::date; I like this way because it avoids conversion between text and integer (once all the constants are parsed). For a more comprehensive guide. Its type is timestamp without time zone. I am converting a postgres app to an Oracle app. where precision is the precision to which you want to truncate the date or time (e. The cast to date ( day::date) does that implicitly. AT TIME ZONE. 9. PostgreSQL provides a number of functions that return values related to the current date and time. I have been trying to simulate the following Oracle statement in PostgreSQL: To reach this, I was already able to simulate the TRUNC () function receiving only one time datatype parameter, which is timestamp without time zone. e. The DATE_TRUNC () function in Postgres truncate a date or time value to a specific precision. . trunc; Date/Time Functions. Use the below command: SELECT date_trunc ('week', timestamp'2021-08-23 19:14:20'); Postgresql date_trunc week. The following illustrates the. SELECT date_trunc($1, purchase_date) unit_of_time, SUM(total) FROM orders WHERE purchase_date >= $2 AND purchase_date <= $3 GROUP BY unit_of_time ORDER BY unit_time; [interval, startDate, endDate] The above query works correctly for when I pass in either 'month' or 'day' as the interval variable, but gives incorrect values. split_part . This is used in subquery cal to generate a list of all dates in your data. If the contraint should apply to the tservice as type "date" you might as well create the tservice column as type "date" instead. Everything to the “right” of the datepart you selected will be “blank” or go back to the beginning (in other words, if you truncate your query at year, then the month, day and time will “reset” to 01-01 00:00). The PostgreSQL formatting functions provide a powerful set of tools for converting various data types (date/time, integer, floating point, numeric) to formatted strings and for converting from formatted strings to specific data types. The quarter of the year (1 - 4) that the date is in. for example 2018-10-15 will be 2018-10-01 and 2018-10-30 also will be 2018-10-01. The range of DATE datatype is from 4713 BC to 5874897 AD. Since this is a performance-critical part of the query, I'm wondering whether this is the fastest solution, or whether there's some shortcut (compatible with Postgres 8. confusingly at time. Right now the cod. For formatting functions, refer to Section 9. 1 Answer. This uses PostgreSQL’s date_trunc () function, along with some date arithmetic to return the results we want. So using date_trunc ('week',now ())-'1 s'::interval; on the right side of your date operator should work. 2020-04-01 , and has the advantage that subsequent steps in the pipeline can read it like a normal date. SELECT EXTRACT(QUARTER FROM TIMESTAMP '2023-03-11 17:43:17. A) Extracting from a TIMESTAMP examples. This list of the. The Oracle TRUNC() function returns a DATE value truncated to a specified unit. Its Java equivalent is: Instant. TRUNC(date, format) Code language: SQL (Structured Query Language) (sql) Arguments. RTRIM (‘abcxxzx’, ‘xyz’) ‘abc’. Here is the syntax of the PostgreSQL date_trunc() function: date_trunc (field TEXT, source TIMESTAMP). All the functions and operators described below that take time or timestamp inputs actually come in two variants: one that takes time with time zone or timestamp with time zone, and one that takes time without time zone or timestamp without time zone. 24: In Postgresql, to truncate or extract the week of the timestamp value, pass the week as a string to the date_trunc function. Which date function I should use to build such an interval? postgresql postgresql-9. 切り捨ては抽出とは異なります。例： タイムスタンプを四半期まで切り捨てると、入力タイムスタンプの四半期の最初の日の真夜中に対応するタイムスタンプが返されます。The PostgreSQL DATE_TRUNC function is used to truncate the date and time values to a specific precision (into a whole value), such as 'year', 'month', 'day', 'hour', 'minute', or 'second', in a string format. Let’s group the table’s data by “DAY” via the DATE_TRUNC () function: SELECT DATE_PART ( 'DAY', publish_date) day_of_month, COUNT. "employees" AS "Employee" WHERE ("Employee". Here is my sql below (This is based on Postgres. 9. 9. Here’s a bit of code adapted from the PostgreSQL wiki that I like for creating the ever necessary date dimension in PostgreSQL. Some details are different for date or timestamptz. , week, year, day, etc. Here's an example: SELECT round (date_trunc ( 'day', your_date_column):: date) AS rounded_date FROM your_table; In this example, replace your_date_column with the actual name of the column that contains the date you want to round, and your_table with the name of the table where the column resides. This. You may try subtracting 3 months from the input date, and then check whether the resulting date fall within the first or second half of the year: SELECT CASE WHEN EXTRACT (month FROM input_date) - INTERVAL '3 MONTH' BETWEEN 1 AND 6 THEN 1 ELSE 2 END AS fiscal_half FROM yourTable; The trick. You can't cast tservice when creating the constraint. (Expressions of type date will be cast to timestamp and can therefore be used as well. The special difficulty of your task: you want the ceiling, not the floor (which is much more common). Here is how I make a standard quarterly score average with default quarter. 9. Julian calendar date (integer days since local midnight on November 24, 4714 BC) Q: quarter: RM: Month in uppercase Roman numerals (I to XII; I is January) rm: Month in lowercase Roman numerals (i to xii; i is January) TZ: Uppercase time zone abbreviation ( to_char supported ) tz: Lowercase time zone abbreviation (only to_char. date_trunc ( field, source [, time_zone ]) source is a value expression of type timestamp, timestamp with time zone, or interval. SELECT date_trunc. PostgreSQL provides a number of functions that return values related to the current date and time. I would suggest not thinking too hard about the problem and just using the first date/time of the month. Your database returned: ERROR: set-returning functions are not allowed in CASE Hint: You might be able to move the set-returning function into a LATERAL FROM item. Isolating hour-of-day and day-of-week with EXTRACT function. First, we have the date part specifier (in our example, 'month'). You can readily convert them to the format you want, get the difference between two values, and so on. The function date_trunc is conceptually similar to the trunc function for numbers. Share. 2: I've chosen "date_period" to be just one day (and, in some places, formatted the result for ease of display). 9. date_trunc. date_trunc () The return type of the date_trunc function is a timestamp. The following shows the syntax of the Oracle TRUNC() function:. 2) and found the date_trunc function extremely useful for easily matching time stamps between certain days/months/etc. For instance, if you add a month to the 31st of January, with add_months,. g. Delaying Execution. SELECT * FROM tbl WHERE start_date <= '2012-04-12'::date AND end_date >= '2012-01-01'::date;I’d like to produce the generic quarter end date for a given date. ) field selects to which precision to truncate the input value. I've looked around and I can't figure out the right syntax for accessing the month and comparing with the current month. g. (. EXTRACT, date_part EXTRACT(field FROM source)The extract function retrieves subfields such as year or hour from date/time values. See the documentation for all values. When using this function, do not think in terms of days. 789'); date_trunc 2020-04-01 00:00:00date_trunc('hour', timestamp '2001-02-16 20:38:40') 2001-02-16 20:00:00: extract. DROP TABLE if exists d_date; CREATE TABLE d_date. The DATE_TRUNC() function will truncate timestamp or interval data types to return a timestamp or interval at a specified precision. Date_trunc function timestamp truncated to a specific precision. ) Details: 'quarter' is not mentioned in the doc as valid fields for date_trunc(). Sorted by: 1. format_datetime(timestamp, format) → varchar. Required. 32 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. Note that the latter. To have one row per minute, even when there's no data, you'll want to use generate _ series. The second one which use DATE_TRUNC will tranc any date to the first day of the month. I assume this is for analytics purpose. 指定した単位（month）以下の値が切り捨てられ、 年 月という結果. These SQL-standard functions all return values based on the start time of the current transaction:What you should do: Order by year and month. "GROUP BY date_trunc also? @Bravo: yes you need to repeat the expression in the group by clause. g. As far as I understand you want to change the day of the month to 8. The DATE_PART () function extracts a subfield from a date or time value. orm: dql: datetime_functions: date_trunc: YOUR_BUNDLE_HEREDoctrineExtensionsDateTrunc. functions. The following bug has been logged online: Bug reference: 2664 Logged by: Yoshihisa Nakano Email address: nakano. The date_trunc(text, timestamptz) variant seems a bit under-documented, so here are my findings:. For formatting functions, refer to Section 9. That will give us an integer that's a multiple of 7. The snippet provided below shows how to use the DATE_TRUNC () function in Postgres: DATE_TRUNC (dateField, timestamp); Specify the date field, such as year, month, day, etc. create or replace function what_quarter_is(date_in date, start_mon_in. date_trunc. table` GROUP BY ddate; LIMIT 100; and maybe withouth the LIMIT clause: SELECT ; DATE_TRUNC (date, < Parameters. extract() complies with the SQL standard, date_part() is a Postgres specific query. You can fix a date or remove days from current day. By Admin August 9, 2023 August 9,. SELECT date_trunc ('quarter', now()); date_trunc-----2021-01-01 00:00:00+00. AS day_of_month, datum - DATE_TRUNC('quarter',datum)::DATE +1 AS day_of_quarter, EXTRACT. DATE_TRUNC (date, < Parameters. These SQL-standard functions all return values based on the start time of the current. How about truncating to the beginning of this month, jumping forward one month, then back one day? =# select (date_trunc ('month', now ()) + interval '1 month - 1 day')::date; date ------------ 2015-07-31 (1 row) Change now () to your date variable, which must be a timestamp, per the docs. You can't cast tservice when creating the constraint. Like for example, I passed a date as on 12th January, 2015, I need the result to be as 4th quarter of 2014. These queries work fine in oracle but am in the process of converting it to a postgres query but it complains. It takes a date part (like a decade, year, month, etc. date_trunc函数根据指定的日期部分（例如小时、周或月）截断一个TIMESTAMP或一个INTERVAL值，并以一定精度返回截断的时间戳或间隔值。[email protected]_trunc ('month',current_date) + interval '1 month' - interval '1 day'. Learn how to round or truncate timestamps in PostgreSQL for effective time-based grouping using the date_trunc function. Syntax: date_trunc ('datepart', field) The datepart argument in the above syntax is used to truncate one of the field ,below listed field type: millennium. I have a table where date | interval juin 1, 2022, 12:00 AM | 0 years 0 mons 0 days 0 hours 1 mins 58. - It retrieves the trimmed part with a specific precision level. Sorted by: 2. 1. 28 shows the available functions for date/time value processing, with details appearing in the following subsections. g. 9. To get week start and end date (as 0 for Monday and 4 for Friday): select cast (date_trunc ('week', current_date) as date) + 0 || '-->' || cast (date_trunc ('week', current_date) as date) + 4; 2015-08-17-->2015-08-21. g. The following are a couple custom functions which allow this configuration. date_trunc ('hour', created) + extract (minute from created)::int / 15 * interval '15' minute. Take two easy steps to create date_trunc: Break down the datetime into small parts (Year, Month, Day/Hour, Minute, Second) and extract the parts you need. - It accepts a “datePart” and a “field” as arguments. To represent an absolute point in time, use a timestamp instead. 30 shows the available functions for date/time value processing, with details appearing in the following subsections. A date does not represent a specific time period; it can differ based on timezones. If you want just the date in the current time zone, cast to a date. It's bad practice but you might be forgiven if you use. For example, if we want just the month from the date 12/10/2018, we would get December (12). CREATE OR REPLACE FUNCTION round_time (timestamp with time zone) RETURNS timestamp with time zone AS $$ SELECT date_trunc ('hour', $ 1) + interval '5 min' * round (date_part ('minute', $ 1) / 5. . of ("Asia/Tehran")). Finally, it returns the truncated part with a specific precision level. Table 9. Format date with to_char; Setup. Consequently, the timestamp will be rounded/truncated based on the specified date field. sql. EXTRACT, date_part EXTRACT(field FROM source) The extract function retrieves subfields such as year or hour from date/time values. Syntax.