For instance, the “BETWEEN” clause, the “DATE_TRUNC()” function, and the basic comparison operators like “=”, “!=”, “>=” etc. Functions and Operators. DROP FUNCTION IF EXISTS DATE_TRUNC; CREATE FUNCTION DATE_TRUNC( in_granularity ENUM('hour', 'day', 'month', 'year'), in_datetime datetime(6) ) RETURNS datetime(6). 4. edited Aug 18, 2015 at 10:57. 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. date) going over the date/time functions in. The table currently has nearly 5 million rows and this query currently takes 8 seconds to execute. These SQL-standard functions all return values based on. I am trying to pull entries which happen after April 1st, 2019. SELECT date_trunc('day', CURRENT_TIMESTAMP), '2017-04-14 00:00:00';. AT TIME ZONE 9. 说明：DATE_TRUNC 函数根据您指定的日期部分（如小时、周或月）截断时间戳表达式或文本。DATE_TRUNC 返回指定的年的第一天、指定的月的第一天或指定的周的星期一。. SELECT DATE_TRUNC('month', TIMESTAMP '2005-05-21 15:30:30'); Result: 2005-05-01 00;00:00 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. century. PostgreSQL 9. Share. The function date_trunc is conceptually similar to the trunc function for numbers. I don't have an explanation for why casting your timestamp to a date doesn't work for you, but try the date_trunc() function instead. Note that the specifier is a string and needs to be enclosed in quotes. Table 9-26 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. If it doesn't work I might try what you said i. Recently, I have been getting familiar with PostgreSQL (using 8. -- date_trunc（日付の切り捨て）の構文 date_trunc( 精度 , 日付・時刻 ); 精度には'year'、'month'、'day'等を指定します。. , line 01 (2011/01/03 19:18:00. l_date is the column where I would pull the date from. Then format date the way you want. It is worth noting that the function list (table 9-27) doesn't mention date_trunc(text, interval) form of date_trunc, it only lists the date_trunc(text, timestamp) version. Current Date/Time. The DATE_TRUNC() function reduces the granularity of a timestamp. Based on the parts extracted, create a new datetime. 9. In this case I use the now() function to return the current date, and the 'month' argument modifies that date to the beginning of. answered Aug 18, 2015 at 10:52. The PostgreSQL date_trunc() function truncates a specified timestamp or interval value to the specified part and returns the result. 2 Answers. first day of year + current week * 7 days = closest preceding date with same day of week as the first day of the year. Because of that, you can't use it in an index. postgresql error: function date_trunc(unknown, text) does not exist LINE 1: SELECT DATE_TRUNC('day', "Date") AS __timestamp, ^ HINT: No function matches the given name and argument types. 8) Postgres DATE_TRUNC() Function. SELECT * FROM stud_cmp WHERE DATE_TRUNC ('day', start_date) = '2020-01-01' :: timestamp; In the above example, after comparing the start date and with date_trunc functions, it will display the three records which contain the comparison. date_trunc('field', source) source is a value expression of type timestamp (values of type date and time are cast automatically). ). If the value is negative, the parts are counted backward from the end of the string. But what exactly are you trying to achieve there? can't you just use intime - (current_date - 1) and use the resulting interval – user3303155. For formatting functions, refer to Section 9. In the above output, it shows the output like a day of the timestamp value but we can find the week number. demo:db<>fiddle. Truncate datetime column in MySQL query. Related: Ignoring time zones altogether in Rails and PostgreSQL;I need to query for a date like the one in my code, and in postgreSQL i found date_trunc to "cut off" unnecessary information from the date. date_trunc ( text, timestamp) → timestamp. Finally… The date_bin function is adaptable and offers many new features on top of what PostgreSQL already has to offer. The full docs in section 9. 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: CREATE FUNCTION end_of_quarter (d date) RETURNS date AS $$ SELECT CAST (date_trunc ('quarter', d) + interval '3 months' -. Follow answered Aug 28, 2015 at 6:57. milliseconds contains seconds & microseconds contains milliseconds (and thus seconds too). date_trunc¶. The trunc () function is used for truncating numbers, not dates. CAST both fields to datatype DATE and you can use a minus: (CAST (MAX (joindate) AS date) - CAST (MIN (joindate) AS date)) as DateDifference. You're storing timestamps, not just dates, and you want to group by day not by number of previous events. 9. The straightforward way to do it is like this: select date_trunc('minute', now()) Edit: This truncates to the most recent minute. Pictorial Presentation of PostgreSQL DATE_TRUNC() function. In Postgresql, date_trunc is used to extract and truncate the specific datepart ( level of precision ) of the date and time like. 9. select * from table where extract (hour from column1) in (8, 9) where cast (column1 as time) >= '8:00' and column1::time < '10:00'. date AT TIME ZONE 'UTC'))? I need to be rounding down to full days (and weeks, etc. I have to convert a postgres query to Sequelize query. 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. "GROUP BY date_trunc also? @Bravo: yes you need to repeat the expression in the group by clause. I want to be able to: apply a mathematical operator to subtract 1 day filter it . , year, month, day, etc. SELECT date_trunc ('day', time), "PositionReport". How to use the date_trunc function for biweekly grouping. 1, compiled by Visual C++ build 1800, 32-bit" The data types of two columns which I am dealing with: eventtime timestamp without time zone sourceid integer NOT NULL Time zone is "Europe/Berlin". SELECT my_date::date::timestamp. The equivalent for your case is date (): select date (created_at), count (*) from requests . 1) 2. I have a slow query that generates a report of account activity per week over the past year. ) from a date or time. A more specific answer is: where generated_time >= date_trunc ('hour', current_timestamp) and generated_time < date_trunc ('hour', current_timestamp) + interval '1 hour'. "GROUP BY date_trunc also? @Bravo: yes you need to repeat the expression in the group by clause. . 1. 0. Syntax: date_trunc (text, timestamp) Return Type: timestamp. 1) 2. Add a comment. 9. The date_trunc() function in PostgreSQL is used to truncate a timestamp or interval value to a specified unit. Popular Course in this category. g. date_trunc(text, timestamp) timestamp: Truncate to specified precision; see also Section 9. Closed. Basically, there are two parameters we. To generate a series of dates this is the optimal way: SELECT t. Current Date/Time 9. 3. Read more about PostgreSQL and time series right now: my blog post about using string encoding to find patterns in timeseries has further. In postgres, you could phrase this as: date_trunc ('quarter', current_date) + interval '3 months' - interval '1 day'. Table 9. You can use this for PostgreSQL. 9. Here’s the current timestamp. Date_Trunc varies parts of the date/time: century, year, month, day, hour, minute, second, millisecond,. So fellow SQL aficionado's how to take the following WHERE clause in PostgreSQL and convert it to SQLite3 without using a compiled extension: WHERE DATE_TRUNC ('day', c. 1. Postgres date_trunc quarter with a custom start month. 32 shows the available functions for date/time value processing, with details appearing in the following subsections. WW truncates date to the nearest previous day same to the first day of week of the year. timestamp)) from rollup_days as rp; To convert the timestamp back to a bigint, use extract ()Select date_trunc('week',dateTime) Date_week, Max(Ranking) Runing_Total_ID from (select datetime, id , dense_rank over (order by datetime) as Ranking from Table1) group by 1 This query is working for me to give me the running total of total IDs by week. Various built-in functions, operators, clauses, etc. As such, it doesn't have any good. Trimming trailing :00 from output after date_trunc. I'm not sure what equivalent are you looking for, but: there is no nanosecond precision in PostgreSQL: The allowed range of p (precision) is from 0 to 6 for the timestamp and interval types. Its Java equivalent is: Instant. , year, month, week from a date or time value. . The date_trunc() function in PostgreSQL is used to truncate a timestamp or interval value to a specified unit. answered Apr 14, 2017 at 7:37. or you can create your own. 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. Let’s add a year to any date. 0. These SQL-standard functions all return values based on the start. You obviously got my point, because you added a remark to your answer that they should use a date column for the month. 9. If I use it like ths: select trunc(now(),'MM'). 4. timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00'. I'm a little confused about using trunc() function in postgresql. "updated_at" BETWEEN '2012-10-17 00:00:00. EXTRACT, date_part 9. This function takes two arguments: the first is the end date and the second is the start date. Basically 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). Viewed 11k times. I will get the same. 2) and found the date_trunc function extremely useful for easily matching time stamps between certain days/months/etc. I think, what you want to do is: SELECT date (updated_at), count (updated_at) as total_count FROM "persons" WHERE ("persons". Multiply it by 1000 to turn it into milliseconds. We had discussed about the Date/Time data types in the chapter Data Types. 4 and i noticed a strange behavior when using date_trunc. It’s absolutely on target. Now, let us see the Date/Time operators and Functions. RTRIM. Extract year from postgres date. The cast to date ( day::date) does that implicitly. 3. PostgreSQL. So using date_trunc('week',now())-'1 s'::interval; on the right side of your date operator should work. 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. This function truncates a date/time value to a specified precision. For. 10. It’s possible in Postgres to truncate or round a given timestamp to some given level of precision. g. Split a string on a specified delimiter and return nth substring. SELECT date_trunc( 'day', to_timestamp(requests. 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. the_date 2000-12-31 00:00 Is there a way to tell date_trunc to do day/month/year conversions based on the timezone it is feeded with? The expected output would be: 2001-01-1 00:00+0100 With PostgreSQL there are a number of date/time functions available, see here. Syntax. You can use this for PostgreSQL. Sorted by: 3. date_trunc('month', '{{ date. This gives the date rounded to the start of the quarter, e. Looks like I could go your way or just go full native query instead. What is the linq equivalent to sql trunc date? 0. 2. If you want just the date in the current time zone, cast to a date. For formatting functions, refer to Section 9. , work with Date objects directly and not use date_trunc. To have one row per minute, even when there's no data, you'll want to use generate _ series. It will return the date truncated to month precision, e. Table 9. So instead of having. atZone (ZoneId. If you prefer to write standard SQL, stick to extract(). SELECT date_trunc ('month', CURRENT_DATE) + interval '1 month - 1 day'; Share. 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. create function end_of_month(date) returns date as $$ select (date_trunc('month', $1) + interval '1 month' - interval '1 day')::date; $$ language 'sql' immutable strict; EDIT Postgres 11+ Pulling this out of the comments from @Gabriel , you can now combine interval expressions in one interval (which makes things a little shorter):I think the :: operator is more common in "Postgres land". Note: All the date field parts other than the targeted. , week, year, day, etc. The below will index but returns with timestamp added to date which. This isn't a general replacement, but it works to remove the time portion of a date. About;. Code:The date/time functions provide a powerful set of tools for manipulating various date/time types. date) going over the. start_date) <= DATE_TRUNC ('day', q. Truncate to specified precision; see Section 9. "updated_at" BETWEEN '2012-10-17 00:00:00. Here’s an example that returns the last day of the current month: SELECT (date_trunc ('month', now ()) + interval '1 month - 1 day'); Result: 2022-04-30 00:00:00+10. This may be a bit sub-optimal, but it works. - The value for the “field” argument must be valid. Using column::timestampt (0) may lead to unexpected rounding up column value. Yes, that is how you use date_trunc. I am wondering if it's possible to truncate dates other than using the default choices using date_trunc. 1) below the day precision (first parameter) the time zone offset of the result is always the same as the second parameters' offset. I want something in between like 100 milliseconds (1/10 second). 1) number The number. Issue in creating a function in PostgreSQL using date_trunc. This macro splits a string of text using the supplied delimiter and returns the. Is that what you want?The date_trunc(text, timestamptz) variant seems a bit under-documented, so here are my findings:. Improve this answer. PostgreSQL provides a number of functions that return values related to the current date and time. Current Date/Time. 31 shows the available functions for date/time value processing, with details appearing in the following subsections. date_trunc関数の第一引数には任意の値を文字列として指定する。. , week, month, and year. date dollars 2016-10-03 1 2016-10-05 1 2016-10-10 1 2016-10-17 2 2016-10-24 2 date_trunc PostgreSQL function equal for mySQL. postgres=# select date(date_trunc('month',current_date)); -- 月初 date ----- 2022-10-01 (1 row) postgres=# select date(date_trunc('month',current_date) + ' 1 month. The below-provided functions retrieve the DateTime values along with the timezone information:. PostgreSQL cung cấp một số hàm trả về giá trị liên quan đến ngày giờ hiện tại. date_trunc() Examples. 1305621628876. PostgreSQL dynamic date_trunc function rounding up exactly to given timestamp. Args:. toLocalDateTime () When you use date_trunc ('day', now () at time zone 'Asia/Tehran') (column tehran_local_start_of_today) it indicates the start of today in Tehran local. If you are looking for. milliseconds. Truncate date in units other than default choices using date_trunc (Postgres 9. date_created) )AS DAY, this is my output 2013-02-04 00:00:00+00. Note that this will return an actual timestamp; from the wording of the question, the actual column has a string, so you will need to cast it to compare: WHERE CAST ("time" as timestamp) < date_trunc ('day', now () - interval '1 month') – IMSoP. date_trunc(text, timestamp) timestamp: Truncate to specified precision; see also Section 9. 0. This can be done in Postgres with. The time zone is variable. For now, I do a workaround using time_bucket('1 day', timestamp) or include it as part of CTE / with, from which I will call the on date_trunc('month', time_bucketed_day_column). Return the relative rank of the current row. These SQL-standard functions all return values based on. この. 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. custom DATE_TRUNC timeframes. Note that some aggregate functions such as AVG (), MIN (), MAX (), SUM (), and COUNT () can be also used as window functions. string_text (required): Text to be split into parts. Share. Try this one: select to_char (trunc_date,'FMMonth YYYY') from ( select distinct date_trunc ('month', orderdate) as trunc_date from table order by trunc_date desc ). 9. This is the query: select to_char (calldate,'Day') as Day, date_trunc (calldate) as transdate, Onnet' as destination,ceil (sum (callduration::integer/60. PostgreSQL provides a number of functions that return values related to the current date and time. Share. In your example, you could use: SELECT * FROM myTable WHERE date_trunc('day', dt) = 'YYYY-MM-DD'; If you are running this query regularly, it is possible to create an index using the date_trunc function as well: The precision values are a subset of the field identifiers that can be used with the EXTRACT() and DATE_PART() functions. The query is not bad, but you can simplify it. NOW in Postgresql - show date only. g. I have TableA and it has a field of time_captured | timestamp without time zone | default now () It is being used to record when data was inserted into the table. 시간값 내림: DATE_TRUNC. I ended up with a select query displaying dates of a week, select ( (date_trunc ('week',current_date)::date) + (i+6)) as week_date from generate_Series (0,6) i; Is there a way to get the result as Monday, Tuesday and so on. Truncate it to the start of the day (still timestamp without time zone ): date_trunc ('day', (now () AT TIME ZONE 'America/New_York')) Get the. PostgreSQL dynamic date_trunc function rounding up exactly to given timestamp. EXTRACT() : century. These SQL-standard functions all return values based on. date_trunc(text, timestamp) timestamp: Truncate to specified precision; see also Section 9. Current Date/Time. date_trunc('month', current_timestamp) gives you the start of "this month" so in March this would be 2021-03-1 as the comparison for the upper limit is done using < it will include everything on the last day of February. Therefore you can use the date_trunc function which turns a precise timestamp into day, week, month, etc. PostgreSQL dynamic date_trunc function rounding up exactly to given timestamp. 0. 0 did not follow the conventional numbering of millennia, but just returned the year field divided by 1000. source is a value expression of type timestamp or interval. Apparently, the PostgreSQL planner does not evaluate functions. Example of grouping sales from orders by month: select SUM(amount) as sales, date_trunc('month', created_at) as date from orders group by date order by date DESC; We have used the date_trunc function with the where clause to compare the date in PostgreSQL as follows. TRUNC (number [, precision]) Code language: CSS (css) Arguments. date_trunc. The DATE_TRUNC () function is particularly useful for time series analysis to understand how a value changes over time. 5-container, as PostgreSQL gives me the same output for both the query with and without the join (which in my opinion is the expected. It will not convert the value to a date. Example 3:. Fully managed, PostgreSQL-compatible database for enterprise workloads. 2: date_trunc('hour', timestamp '2001-02-16 20:38:40') 2001-02-16 20:00:00:. If we want to look at order growth month over month, we’d use a truncation function in Postgres: #Truncate date specificity SELECT DATE_TRUNC(order_time, ‘month’), COUNT(*) as count_orders FROM orders GROUP BY 1 ORDER BY 1 DESC The DATE_TRUNC() function grabs the month and year from the date so you can get a. Here you can find its API Docs. create function end_of_month(date) returns date as $$ select (date_trunc('month', $1) + interval '1 month' - interval '1 day')::date; $$ language 'sql' immutable strict; EDIT Postgres 11+ Pulling this out of the comments from @Gabriel , you can now combine interval expressions in one interval (which makes things a little shorter): However, date_trunc('day', created) is not equivalent to the other expressions, because it returns a timestamp value, not a date. However we know that date_trunc('month', mydate)::date is safe because it. com> Reviewed-by: Tom Lane. g. Sorted by: 5. SELECT cast (created_at as date) as created_at, count (created_at) FROM forms group by 1 ORDER BY created_at asc; If you want the date in a particular time zone, date_trunc with that time zone then cast to a date. This uses PostgreSQL’s date_trunc() function to return the results we want. date 、 time 、または timestamp を指定された精度に切り捨てます。. Create Postgresql index with date_trunc. 忘備録として。. 7. The date part to which to truncate the timestamp value. Finally… The date_bin function is adaptable and offers many new features on top of what PostgreSQL already has to offer. EXTRACT (MONTH FROM input) AS "Month". Trimming trailing :00 from output after date_trunc. 9. Modified 10 years, 9 months ago. SELECT EXTRACT(EPOCH FROM TIMESTAMP '2011-05-17 10:40:28. ExampleHere's the best GROUP BY query I have so far: SELECT d. Very unlikely to change though. 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 date_trunc 関数は概念的に数値に対する trunc 関数と類似しています。 date_trunc('field', source) source はデータ型 timestamp の評価式です(データ型 date と time は自動的にキャストされます)。field は timestamp の値をどの精度で切捨てるかを選択します。返り値の. Its return type is TIMESTAMP with TIMEZONE. Summary: in this tutorial, we will introduce you to the PostgreSQL DATE_PART() function that allows you to retrieve subfields e. This is a timestamp with time zone value which refers in fact to. 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. We’ll use it for different intervals to see the result. The DATE_TRUNC() function will truncate timestamp or interval data types to return a timestamp or interval at a specified precision. 9. Below query is working to get weekly summary. The query below shows sample data of your user adding an other user with a session over two days (to demonstrate the principle) The subquery day_cnt calculates the minimal start date of the sessions and the count_days that is covered with the sessions. I edited my full query into my post now. postgres sql, date_trunc without extra zeroes. Last updated at 2013-05-31 Posted at 2013-05-31. In this case, it is used to truncate the result of the subtraction operation to seconds. 1. The field determines which date/time part will be extracted/pulled out from the given source. I use this in a group by query to get a count for a certain amount of dates. I just want to point out that it is often convenient to leave the value as a date. It can also return a number truncated to the whole number if no precision is defined. In PostgreSQL, DATE_TRUNC Function is used to truncate a timestamp type or interval type with specific and high level of precision. (Values of type date and time are cast automatically to timestamp or interval, respectively. 0) $$. Example: PostgreSQL DATE_TRUNC() function : Example: Code: SELECT date_trunc('hour', timestamp. This function helps in manipulating numbers as required. Author: John Naylor <john. create index concurrently index_requests_on_request_time_in_chicago on requests (timezone('america/chicago', request_time)) After creating the index and re-running with. Modified 1 year, 7 months ago. We’ll use it for different. 18. This is not in any of other answers, which suggest to_char() and date_trunc(). If so, use date_trunc(): select date_trunc('month', order_date) as yyyymm If you really want a string, you should accept Nick's answer. (Values of type date and time are cast. Table 9. However, you can set the time portion of a timestamp, dropping the date portion entirely with date_trunc. Also avoids misunderstandings general communication. Luckily, Postgres has functional indexes, and this fit the bill perfectly - we needed to index the request_time column in the display time zone. date_trunc can be really helpful if you want to roll up time fields and count by day or month. Pad on the right of a string with a character to a certain length. With PostgreSQL there are a number of date/time functions available, see here. 7) PostgreSQL Now (): Display without milliseconds. PostgreSQL Version: 9. 9. ) field selects to which precision to truncate the input value. 3. 18. But in the check constraints, I see that the truncated date is being shifted. day. Data granularity measures the level of detail in a data structure. 2014-05-09 16:03:51 will be returned as 2014-05-01 00:00:00. PostgreSQL provides a number of functions that return values related to the current date and time. (In our example, we used month precision. If you want a date/time value (=timestamp) where the time part is 00:00:00 then you can use current_date::timestamp or date_trunc('day', current_timestamp). g. Syntax. Syntax. PostgreSQL releases before 8. How to truncate seconds from a column (timestamp) in PostgreSQL without using date_trunc function. A função DATE_TRUNC do Postgres pode nos ajudar a “truncar” uma data, bem, mas o que isso quer dizer? É simples, ela retorna a data inicial de um intervalo. However, Postgres' date type does Table 9. You could think of it as a date version of the trunc() function (which truncates numbers). - DATE_TRUNC(): Truncates/trims unnecessary values from the DateTime and retrieves a result with specific precision. It takes a date part (like a decade, year, month, etc. Test case: SELECT (CAST (MAX (joindate) AS date) - CAST (MIN (joindate) AS date)) as DateDifference FROM generate_series ('2014-01-01'::timestamp, '2014-02-01'::timestamp, interval '1 hour') g. PostgreSQL has a rich set of native data types available to users. The date part to which to truncate the timestamp value. ADVERTISEMENT. 0. RTRIM (‘abcxxzx’, ‘xyz’) ‘abc’. The query worked fine in principle so I'm trying to integrate it in Java. This way, timescaledb's gapfill function from smaller interfal (day) should be carried on the longer time interval. 1 Answer. So current_date - 1 would be enough. Sorted by: 1. 000000の場合Postgres has plenty of date-specific functions -- from date_trunc() to age(). ) field selects to which precision to truncate the input value. 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. POSTGRESQL Course Bundle - 5 Courses in 1 | 1 Mock Test. This function can be used to round the timestamps to the required interval, say year, day, hours or seconds. Date/Time Functions and Operators. ShareTeams. PostgreSQL - DATE/TIME Functions and Operators. SELECT '2022-09-18':: date + INTERVAL '1 year'; In the above code, We have used typecast (::) operator to convert a value of one datatype into. date_trunc('field', source) source is a value expression of type timestamp (values of type date and time are cast automatically). 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. EDIT: Perhaps the better solution for these two databases is: select cast (created_at as date)This worked perfectly! Would be really nice to have as a first class citizen in EF. the postgres server timezone. date_trunc('field', source) source is a value expression of type timestamp or interval. For formatting functions, refer to Section 9. , hour, week, or month and returns the truncated timestamp or interval with a level of precision. PostgreSQL : Converting timestamp without time. If so, use date_trunc(): select date_trunc('month', order_date) as yyyymm If you really want a string, you should accept Nick's answer. The function date_trunc is conceptually similar to the trunc function for numbers. Date_trunc by month? Postgresql. date_trunc(text, timestamp) timestamp: Truncate to specified precision; see also Section 9. update foo set created_at = date_trunc('second', created_at) where created_at is not null; Instead of using date_trunc you can also just cast the value: created_at::timestamp(0) for the update statement, or current_timestamp::timestamp(0) in the default value. Extract year from postgres date. Let’s see the following example. If you're certain that column should always store only the first of a month, you should also use a CHECK constraint. Yes, that is how you use date_trunc.