Postgresql extract monthYear from a date to be compared. As one gets converted to the other, there is absolutely no performance difference. 9. extract() complies with the SQL standard, date_part() is a Postgres specific query. Apr 20, 2017 at 8:39. date_created <= { {date_range_end. : select date_trunc_interval('15 minutes', timestamp '2020-02-16 20:48:40'); date_trunc_interval ----- 2020-02-16 20:45:00 (1 row) With this addition, it might be possible to turn the existing. “Year” must be passed. EXTRACT, date_part EXTRACT (field FROM source) The extract function retrieves subfields such as year or hour from date/time values. EXTRACT, date_part. , week, month, and year. You can compare the month and year of a date with the current one. That will give us an integer that's a multiple of 7. The date_trunc function truncates a TIMESTAMP or an INTERVAL value based on a specified date part e. source must be a value expression of type timestamp, time, or interval. 所以在此只说明Postgresql 中的TRUNC取断函数. 9. date_trunc¶ pyspark. , hour, week, or month and returns the truncated. 표현범위는 BC. select date_trunc('hour', current_timestamp) + date_part('minute', current_timestamp)::int / 15. Manipulating the current date and time 100 XP. I've tried a few ways in my controller:I'm looking for a single function which I can substitute for date_part in this query so that it returns 65: select date_part('minutes', '65 minutes'::interval);. Update. The default quarter starts with January. , year, month, week from a date or time value. 9. g. SELECT * FROM tbl WHERE start_date <= '2012-04-12'::date AND end_date >= '2012-01-01'::date;The output snippet shows that the DATE_PART() function pulls out the year from the given date. The basic syntax of the DATE_TRUNC function is as shown below: DATE_TRUNC(precision, source); where precision is the precision to which you want to truncate the date or time (e. source must be a value expression of type timestamp, time, or interval. Ask Question Asked 10 years, 5 months ago. ON d_date(date_actual); COMMIT; INSERT INTO d_date: SELECT TO_CHAR(datum, 'yyyymmdd')::INT AS date_dim_id, datum AS date_actual, EXTRACT(EPOCH FROM datum) AS epoch, TO_CHAR(datum, 'fmDDth') AS day_suffix, TO_CHAR(datum, 'TMDay') AS day_name, EXTRACT(ISODOW FROM datum) AS day_of_week, EXTRACT(DAY. One addition: If the timestamp field is indexed, using dt::date or CAST(dt AS date) prevents the index from being used. 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. Using EXTRACT 100 XP. g. Elasticsearch SQL accepts also the plural for each time unit (e. Snowflake has the simply function Quarter(timestamp()) which returns current quarter, but wondering how to do day of QTR , all tutorials reference Postgres/ sql server. In PostgreSQL, DATE_TRUNC Function is used to truncate a timestamp type or interval type with specific and high level of precision. 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. 3. 9. Syntax. 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. , week, year, day, etc. ) from a date or time. 29 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. g. PostgreSQL provides a number of functions that return values related to the current date and time. Delaying Execution. start }}'::timestamp) The result of that is a timestamp from which you can subtract the interval: date_trunc. First, we have the date part specifier (in our example, 'month'). Say,. trunc; Date/Time Functions. source must be a value expression of type timestamp, time, or interval. You should be familiar with the background information on date/time data types from. The date is complete (year, month, and day). ) field is an identifier or string that selects what field to extract. 9. GROUP BY date_trunc('day', datelocal) ORDER BY date_trunc('day', datelocal); A bit more noisy code, but faster (and possibly easier to optimize for the query planner, too). , date/time types) we describe the actual behavior in subsequent sections. I think the shortest and most elegant way to solve this issue is to use date_trunc('quarter',d) (which will retrieve the start of the quarter) + 3 months - 1 day, and use the expression to create a FUNCTION:. The return value is of type timestamp with all fields that are less than. ) This function takes two arguments. 9. 9. 12,516 ExpertMod8TB. This chapter describes most of. 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. g. And it works. 2-1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 10. Note: All the date field parts other than the targeted. 0. 9. date 、 time 、または timestamp を指定された精度に切り捨てます。. The quarter of the year (1–4) that the date is in SELECT EXTRACT(QUARTER FROM TIMESTAMP '2001-02-16 20:38:40'); Result: 1. PostgreSQL is a powerful database and includes various functions for managing timestamps and date times. 9. I need to find the value of the previous quarter for a particular given date. If I want to group a column of timestamps, say registered_at by the day on which they occurred, I can use either date_trunc('day', registered_at) or registered_at::date. You. ) Details: 'quarter' is not mentioned in the doc as valid fields for date_trunc(). ← PostgreSQL timeofday () Function PostgreSQL to_timestamp () Function →. (Expressions of type date are cast to timestamp and can therefore be used as well. Name of the column: This is defined as the name of the column we used with the date_trunc and to_char functions. 9. The PostgreSQL to_date () function. But there is also no point in casting date literals to date as input parameter. QUARTER: The calendar quarter of the specified date as an integer, where the January-March quarter is 1. is out of the question as this forces quarters to start on Jan 1st and it has 'hardcoded' quarter starting dates (Apr 1st, Jul 1st, etc). source must be a value expression of type timestamp, time, or interval. Saved searches Use saved searches to filter your results more quicklyPostgresql SQL GROUP BY time interval with arbitrary accuracy (down to milli seconds) I want to aggregate data at 5 minute intervals in PostgreSQL. So if I run the SQL now, it should give me sep 30 2012. In fact, DATE_TRUNC is returning the beggining of the month FOR THE WORKING TIME ZONE, but I need to know, in my timezone, what is the begginning of the UTC month. 首先介绍一下Oracle的trunc函数:. (Expressions of type date will be cast to timestamp and can therefore be used as well. select cast (date_trunc ('month', current_date) as date) 2013-08-01. DROP TABLE if exists d_date; CREATE TABLE d_date. I would like to change the date into month. The function date_trunc is conceptually similar to the trunc function for numbers. Postgres Pro provides a number of functions that return values related to the current date and time. Be aware of corner case pitfalls with type timestamp (or date ) depending on the current time zone setting (as opposed to timestamptz ). ) field selects to which precision to truncate the input value. 9. quarter; year; decade; century; millennium; source. 26 lists them. all that have at least one day in common. Example 2: Truncate a TIMESTAMP value to the beginning of the hour. PostgreSQL provides the extract function to get a date's year and week number according to the ISO 8601 standard, which has the first week of every year containing January 4th. Postgres에서 DATE_TRUNC (). The syntax of the function is as follows: DATE_TRUNC ('precision', expression); where expression is a timestamp or an interval to truncate. Hide Details. DATE_TRUNC() will return an interval or timestamp rather than a number. This uses PostgreSQL’s date_trunc () function, along with some date arithmetic to return the results we want. EXTRACT, date_part. For tuning HLL, review log2m, regwidth, and expthresh which can increase accuracy but will impact storage time and performance. Finding events relative to the present time with NOW () and CURRENT_DATE functions. Table 9. decade. 6. What it does: The Redshift add_months function adds months, specified by integer to a date value. Table 9. Table 9-26 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. Understand the functions and time units to effectively manipulate temporal data in your queries. I need to take a DateTime value (apparently timestamp in Postgres) and determine the last quarter hour value. Return value. CURRENT_DATE: DATE: Return the current date: CURRENT_TIME: TIMESTAMPTZ: Return the current time: CURRENT_TIMESTAMP: TIMESTAMPTZ: Return the current date and time with time zone at which the current transaction starts: DATE_PART: DOUBLE PRECISION: Get a field of a timestamp or an interval e. 9. 000000' AND '2012-11-07 12:25:04. I am trying to use the Date_Trunc for MONTH function in a SQL statement but somehow it is not working for me. 1) below the day precision (first parameter) the time zone offset of the result is always the same as the second parameters' offset. SELECT date_trunc ('quarter', now()); date_trunc-----2021-01-01 00:00:00+00. 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. Sorted by: 0. 2 Answers. --set the first day of the week in. Here is the syntax of the PostgreSQL date_trunc() function: date_trunc (field TEXT, source TIMESTAMP). In the above output, it shows the output like a day of the timestamp value but we can find the week number. 1. 3. ). DATE_TRUNC returns a date or timestamp, while DATE_PART returns a subfield from a date or timestamp. source is a value expression of type timestamp or interval. New in version 2. Explained below with examples: Example 1: Fiscal Year system: Apr to Mar From Date: Jan-05-2008 To Date: May-15-2008. Finally, it returns the truncated part with a specific precision level. 1. date=to_char (date_trunc ('day', se. Previous. 9. The documentation shows following usage example: SELECT date_trunc('hour', TIMESTAMP '2001-02-16 20:38:40'); Result: 2001-02-16 20:00:00 So I thougt this should work:date_trunc('hour', interval '2 days 3 hours 40 minutes') 2 days 03:00:00: extract. 5. g. You can also use add_months to subtract months by specifying a negative integer. , ‘year’, ‘quarter’, ‘month’, ‘day’, ‘hour’, ‘minute’, ‘second’, etc. Args:. Here’s a bit of code adapted from the PostgreSQL wiki that I like for creating the ever necessary date dimension in PostgreSQL. date_created)::date, 'Month YYYY') as "Month / Year", count (distinct l. The TRUNC() function accepts two arguments:. AT TIME ZONE 9. so you can distinct it first in the table then do the count. DATE_TRUNC ('month','2020-09-12 15:23:00+05:45') gives 2020-09-01 05:45:00+05:45. I see that date_trunc function returns timestamp and intervals cannot be cast to date type: select current_date -. dim_time__month_start_date date NOT NULL, dim_time__week_start_date date NOT NULL, dim_time__quarter_start_date date NOT NULL, dim_time__year_start_date date NOT NULL, The redundant columns wouldn't even help performance of the query at hand. confusingly at time. SELECT date_trunc. create index mytable_ts_day on mytable (extract (day from ts)) and this index then can be used for a matching expression like extract (day from ts) = 9, or any other operator on. The function always returns a DATE. select date_trunc ('minute', created_at), -- or hour, day, week, month, year count(1) from users group by 1. However, date_trunc('day', created) is not equivalent to the other expressions, because it returns a timestamp value, not a date. ) This function takes two arguments. 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。 AT TIME ZONE. You need to remove the concat () as it turns the timstamp into a varchar. time은 시간정보만. Within the Extract keyword we have to mention QUARTER as we are getting quarter from timestamp. 文章浏览阅读9. ) field selects to which precision to truncate the input value. select date_trunc('month',current_date)::date; ┌────────────┐ │ date_trunc │. date_trunc 9. In the attached patch for the March commitfest, I propose a new function date_trunc_interval(), which can truncate to arbitrary intervals, e. Postgres quarter function. These SQL-standard functions all return values based on the start. Write queries for continuous periods as explicit range condition. 1 Answer. I am trying to get only date without time in postgres from the following statement: select current_date - date_trunc ('day',interval '1 month'); But returns me that: 2023-02-07 00:00:00. In this article, we are going to focus on the following concepts. (Values of type date and time are cast. The date_trunc() function in PostgreSQL is used to truncate a timestamp or interval value to a specified unit. 基本的な使い方を見ていこう。. The second one which use DATE_TRUNC will tranc any date to the first day of the month. I'm making my first laravel project, using postgres, and I'd like to be able to access all the people with a birthday this month (my people table has a birthdate field that's a date). 这是 PostgreSQL date_trunc() 函数的语法： date_trunc ( field TEXT , source TIMESTAMP ) -> TIMESTAMP date_trunc ( field TEXT , source TIMESTAMPTZ , time_zone TEXT ) -> TIMESTAMPTZ date_trunc ( field TEXT , source INTERVAL ) -> INTERVAL SELECT DATE_TRUNC('quarter', TIMESTAMP '20200430 04:05:06. We are also looking at upgrading to a newer version of Postgres but that is further out. I can classify the year by quarter using the Postgres keyword QUARTER as illustrated in the documentation just like SELECT EXTRACT(QUARTER FROM TIMESTAMP '2001-02-16 20:38:40');. PostgreSQL provides a large number of functions and operators for the built-in data types. Or simpler, use the column number: group by 1 (if the expression is the first column in the select clause). 5. The DATE_PART function can also be very useful. Formats timestamp as a string using format. All the same can be achieved by using something such as date_trunc('week', date_time) AS date_period, to summarize by weeks instead of days, instead of the definition I used. The DATE_TRUNC () function in Postgres truncate a date or time value to a specific precision. 9. 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. order_date) AS interval FROM orders WHERE orders. source must be a value expression of type timestamp, time, or interval. 2. - The value for the field. Get the last day of the current quarter as a DATE value: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. 9. Given a From Date, To Date and a Fiscal Year system, I want to get all the split-up duration within the given From & To Date based on the Fiscal Year system. Let's see: = $ SELECT date_bin ('5 minutes', now ()); ERROR: FUNCTION date_bin (UNKNOWN, TIMESTAMP WITH TIME zone) does NOT exist. yml. date_trunc('day', timestamptz '2001-02-16 20:38:40+00', 'Australia/Sydney') → 2001-02-16 13:00:00+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. ) field is an identifier or string that selects. Date trunc will convert the data per day wise. I have an sql query am trying to make to my postgres db. 3 . CREATE FUNCTION end_of_quarter (d date) RETURNS date AS $$ SELECT CAST(date_trunc('quarter', d) + interval '3 months' -. timestamp는 날짜와 시간값을 저장하는 8바이트 값이다. LOCALTIME(precision) Arguments. (Values of type date and time are cast automatically to timestamp or interval, respectively. 4. I would suggest not thinking too hard about the problem and just using the first date/time of the month. And I have set up partition table for every month. 5. 8. I think you are looking for the date_trunc () function, which is used to truncate timestamps. 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。AT TIME ZONE. ) as we did for the EXTRACT code. select * from your_table where extract (YEAR FROM createdAt) = extract (YEAR FROM now ()) and extract (MONTH FROM createdAt) = extract (MONTH FROM now ()) Share. Example 3:. currently I am coding the exact date for the last quarter, the quarter before and the quarter one year ago. ). , and a timestamp. I have a table with a date field in timestamp format (ex: 2016-11-01 00:00:00). Truncate to specified precision in the specified time zone; see Section 9. 16. The date_trunc function truncates a TIMESTAMP or an INTERVAL value based on a specified date part e. 7. Postgres date_trunc quarter with a custom start month. 0. These SQL-standard functions all return. source is a value expression that evaluates to type timestamp or interval. 5. It takes 4 bytes of memory to store any date value in PostgreSQL. g. Rabbit. created_at as timestamp) at time zone '+08:00'))::DATE AS period_start FROM transactions LIMIT 1. Connect and share knowledge within a single location that is structured and easy to search. 1. This function allows us to extract a date part and group the records by date/time using the GROUP BY clause. We had discussed about the Date/Time data types in the chapter Data Types. 1994-10-27. g. CREATE TABLE dim_date ( dim_date_id INT NOT NULL, date_actual DATE NOT NULL, epoch BIGINT NOT NULL, day_suffix VARCHAR(4) NOT NULL, day_name VARCHAR(9) NOT NULL, day_name_tr VARCHAR(9) NOT NULL,. format_datetime(timestamp, format) → varchar. Here is the syntax of the PostgreSQL date_trunc() function: date_trunc (field TEXT, source TIMESTAMP). Therefore, your line should read: WHERE job_date >= DATE_TRUNC ('month', '2019-04-01'::timestamp) If you wish to have the. Syntax: DATE_TRUNC ('datepart', field) Datepart can include. day::date FROM generate_series (timestamp '2004-03-07' , timestamp '2004-08-16' , interval '1 day') AS t (day); Additional date_trunc () is not needed. In order to Get quarter from Timestamp in postgresql we use Extract Keyword. 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. It can be of timestamp, timestamptz, or interval type. Table 9. I. PostgreSQL provides a number of functions that return values related to the current date and time. select extract (isoyear from current_date); select extract (week from current_date); But there seems to be no inverse. Both interval and date_trunc have helped me write more effective SQL queries and answer thorny questions about app data. 8. In Postgresql, to truncate or extract the week of the timestamp value, pass the week as a string to the date_trunc function. The precision values are a subset of the field identifiers that can be used with the EXTRACT() and DATE_PART() functions. EXTRACT (field FROM source) The extract function retrieves subfields such as year or hour from date/time values. source is a value expression of type timestamp or interval. DATE_TRUNC() will return an interval or timestamp rather than a number. date_trunc. Delaying Execution. 1 Answer. TRUNC(date, format) Code language: SQL (Structured Query Language) (sql) Arguments. LastAccessDate), quarter = DATETRUNC(QUARTER,. 4. We have converted date column data. created_at)) day when @timeinterval = 'year' then makedate (year (u. Use the function date_trunc() instead,. Truncate to specified precision in the specified time zone; see Section 9. Assuming you want all "overlapping" time periods, i. 789'); date_trunc 2020-04-01 00:00:00 Truncate the input timestamp to the first day of a year. ⬇️ Please click the 👍 reaction instead of leaving a +1 or update? comment2. But the index by field will not be used, you can build a separate index by year and month for this. date_trunc('field', source) source is a value expression of type timestamp (values of type date and time are cast automatically). Even if extracting fields from a date would always produce results that could fit in an integer, according to the doc, extract doesn't directly work on a date type:. "updated_at" BETWEEN '2012-10-17 00:00:00. Postgres では、 DATE_TRUNC () には次の間隔. SELECT * FROM Conference WHERE date_start >= date_trunc ('month', current_date - interval '1' month) and date_start <. (2) as CONCAT_WS appears to require text, not numeric input, you may have to do something like mutate (the_year = as. Also, we can calculate time intervals using these functions that will help us analyze what has changed between those two timeframes. The table currently has nearly 5 million rows and this query currently takes 8 seconds to execute. Note that to_date () returns a date so. The following are a couple custom functions which allow this configuration. 9. SELECT EXTRACT (YEAR FROM TIMESTAMP '2001-02-16 20:38:40'); Result: 2001. Some common precisions are year, month, week, day, hour or minute. In Postgresql, to truncate or extract the week of the timestamp value, pass the week as a string to the date_trunc function. EXTRACT (field FROM source) The extract function retrieves subfields such as year or hour from date/time values. Note that the latter. 2. Overall, it’s a great function to use to help you aggregate your data into specific date parts while keeping a date format. It also uses this format for inserting data into a date. SELECT date_trunc('MONTH', CURRENT_DATE) + INTERVAL '1 MONTH - 1 DAY';I want to generate a series of months. I want to be able to: apply a mathematical operator to subtract 1 day filter it . Date/Time Functions. The quarter of the year (1 - 4) that the date is in SELECT EXTRACT(QUARTER FROM TIMESTAMP '2001-02-16 20:38:40'); Result: 1. In order to group our orders by month, in PostgreSQL we'll use the date_trunc built-in function. Table 9. date 、 time 、または timestamp を指定された精度に切り捨てます。. 8. and source is the date. Thanks @emilie I took a look at the date dimension code that you referenced. The function date_trunc is conceptually similar to the trunc function for numbers. Extract quarter from Timestamp in Postgresql. If you're certain that column should always store only the first of a month, you should also use a CHECK constraint. Syntax: date_trunc. example: SELECT date_trunc ('hour', time 'columnName') from tableName. Hey so im trying to query from a database, using Sequelize (Node. The lowest and highest values of the DATE data type are 4713 BC and 5874897 AD. Also, you need to study the week in snowflake. 28 shows the available functions for date/time value processing, with details appearing in the following subsections. The precision values are a subset of the field identifiers that can be used with the EXTRACT() and DATE_PART() functions. Current Date/Time. Q&A for work. functions. You can round off a timestamp to one of these units of time: microsecond. RTRIM. These SQL-standard functions all return values based on the start. Nice. You can extract the day part of the date and check its value. Both are b-tree indexable operations. quarter; year; decade; century; millennium; source. Ex:If I have 2010-01-01, I would like to return 2010-03-31, and so on. , hour, week, or month and returns the truncated timestamp or interval with a level of precision. Because I have a table that contains time without time zone. PostGreSQL : date_trunc() returns timestamp with timezone when used on date. These queries work fine in oracle but am in the process of converting it to a postgres query but it complains. The LOCALTIME function takes one optional argument:. - It accepts a “datePart” and a “field” as arguments. SELECT DATE_TRUNC ('quarter', current_date ()); Copy. 1) date The date argument is a DATE value or an expression. 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. EXTRACT, date_part 9. 6. answered Aug 18, 2015 at 10:52. If you need to, you can have your own in the following ways as a. For example: Truncating a timestamp down to the quarter returns the timestamp corresponding to midnight of the first day of the quarter for the input timestamp. ) inside sql (. The quarter of the year (1–4) that the date is in. PostgreSQL DATE_PART () function is mainly used to return the part of the date and time; the date_part function in PostgreSQL will subtract the subfield from the date and time value. 28 shows the available functions for date/time value processing, with details appearing in the following subsections. g. Working with the current date and time 100 XP. #. The DATE_PART () function can also be used to group the data by date/time. This is one way to go about it. Date/Time Functions and Operators. Two options: (1) wrap CONCAT (. 9. Saved searches Use saved searches to filter your results more quickly date_trunc ( text, timestamp with time zone, text) → timestamp with time zone. This can be generalized to any type of grouping. interval but not a specific interval like 5 minute or 5 days. It takes two parameters, a “field” and a “source”. g. I am using Datagrip for Postgresql. May I make a request that "Quarter" should be treated as a valid Interval (as a synonym for "3 months"), to be consistent with other date functions that allow it, such as date_trunc() and extract() ? #1. date_trunc ('hour', created) + extract (minute from created)::int / 15 * interval '15' minute. The special difficulty of your task: you want the ceiling, not the floor (which is much more common). The PostgreSQL LOCALTIME function returns the current time at which the current transaction starts. the Use of the DATE_TRUNC() Function in PostgreSQL. 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. DATE_PART. Java date functions. SELECT date_trunc('month',"BDATE") MTH, COUNT("CUSTOMER_REQUEST_ID") DELIVERIES FROM orders GROUP BY MTHSyntax: add_months(date, integer). The function date_trunc is conceptually similar to the trunc function for numbers. You should be familiar with the background information on date/time data types from. Share. 0. To get sales from the first day of the month, we can use the DATE_TRUNC function. Date_trunc. ts BETWEEN a AND b is just a shorthand for writing ts >= a and ts <= b. To build a new timestamp from the date part of the appointment_date and the time value, just add them: appointment_date::date + appointment_end_time::time. The full-list is available in the Postgres docs. date_trunc('hour', interval '2 days 3 hours 40 minutes') 2 days 03:00:00:. created_at as timestamp) So your final query should be something like: SELECT (date_trunc ('day', CAST (transactions. The date_trunc function returns a TIMESTAMP or an INTERVAL value. Take a look at AT TIME ZONE described just below date_trunc in the link above, you could use something like. Practical examples would include analyzing company’s quarterly. Getting the first day is easy and can be done with date_trunc. Note that the 'first day of the week' is not uniform across databases.