3 Answers. ). Modified 10 years, 9 months ago. date_trunc('hour', timestamp '2001-02-16 20:38:40') → 2001-02-16 20:00:00. SELECT my_date::date::timestamp. For. Part of AWS Collective. Exercise care with lower. For instance, the “BETWEEN” clause, the “DATE_TRUNC()” function, and the basic comparison operators like “=”, “!=”, “>=” etc. e. Replicate Oracle's `TRUNC(DATE, 'WW')` behaviour in PostgreSQL. com> Reviewed-by: David Fetter <[email protected] do mention both forms though. , ages of people, years of services of employees, etc. time_zone Hibernate property to the value of UTC. Truncate datetime column in MySQL query. PostgreSQL dynamic date_trunc function rounding up exactly to given timestamp. WHERE job_date >= DATE_TRUNC('month', '2019-04-01'::timestamp) If you wish to have the output as a date, append ::date: SELECT DATE_TRUNC('month', '2019-05-07'::timestamp)::date 2019-05-01 Also, note that the date converts into a timestamp as at midnight. the date, from the provided timestamp. PostgreSQL offers various built-in functions to group data by time, such as the DATE_TRUNC(), EXTRACT(), and DATE_PART() functions. How to import CSV file data into a PostgreSQL table. Users can also define their own functions and operators, as described in Part V. 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. I created a postgres sql function which perform truncate and then insert rows into table. and while the condition is > '2018-10-01' then all dates in the month October will not be shown in the result. The lowest and highest values of the DATE data type are 4713 BC and 5874897 AD. source is a value expression of type timestamp or interval. TRUNC (number [, precision]) Code language: CSS (css) Arguments. 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+0100Postgresql SQL GROUP BY time interval with arbitrary accuracy (down to milli seconds) I want to aggregate data at 5 minute intervals in PostgreSQL. I can't believe the accepted answer has so many upvotes -- it's a horrible method. 0. The TRUNC function has the signature:. Exercise care with lower. The trunc () function is used for truncating numbers, not dates. println("Everything is ok"); return result; and I see "Everything is ok" on the console. passing trunc_date postgres timestamp to php date leads to wrong date. Asked 10 years, 9 months ago. Isolating hour-of-day and day-of-week with EXTRACT function. For example, if I have a table that looks like this. The result should be change to the nearest time i. +01 +02 etc depends on your time locale's daylight saving rules. Postgres has lots of functions for interval and overlap so you can look at data that intersects. Query between two dates and two times. Query between two dates and two times. pdb = conversion to double precision - all decimals restored. The function date_trunc is conceptually similar to the trunc function for numbers. The first removes the hours and smaller units from the timestamp, but still returns a timestamp, while the latter returns the timestamp cast to a date. data for 2); return NEW; end; $$; create trigger mytable_data_truncate_trigger before insert or. source is a value expression of type timestamp or interval. After truncation, the table will appear empty to concurrent transactions, if they are using a snapshot taken before the truncation occurred. 2018 00:00:00 Recently, I have been getting familiar with PostgreSQL(using 8. (note that you need to remove the hour keyword if you use an interval with hours and minutes)This way you just truncate it, without assuming anything about the digits. The date_trunc function uses field either millisecond or second, but millisecond is too small for me and second too large. SELECT (date_trunc ('MONTH', '2019-02-28'::timestamp) + INTERVAL '2 MONTH - 1 day'); Note: If you are using this in a query then you are probably better to get the first day of the following month so your query can say where xxx > month1 and xxx < followingmonth (otherwise you end up losing the last days data). I'm using the driver org. This is a timestamp with time zone value which refers in fact to. . 19, earlier I have made the following Query. Sorted by: 3. execute("TRUNCATE " + tableName); System. 10. 1. Drop the database. datepart. Use the DATE_TRUNC() function if you want to retrieve a date or time with a specific precision from a PostgreSQL database. Date/Time Functions. yml. (Expressions of type date are cast to timestamp and can therefore be used as well. (In our example, we used month precision. The DATE_TRUNC() function will truncate timestamp or interval data types to return a timestamp or interval at a specified precision. The basic syntax of the DATE_PART function is as shown below: DATE_PART(field, source); where field is the. Table 9-2 shows the available mathematical operators. : 2013-05-03 12:20:00). 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). custom DATE_TRUNC timeframes. , week, month, and year. SELECT DATENAME (Month, date_contact) FROM YourTable; OR. 2. 1. Viewed 11k times. In this case I use the now() function to return the current date, and the 'month' argument modifies that date to the beginning of. date_trunc “truncates” a TIMESTAMP or an INTERVAL value based on a specified date part (e. Users coming from Oracle will recognize this one. Let's say you have a simple query that groups by week and looks back at the last 4 weeks: select date_trunc ('week', created_at), -- or hour, day, month, year count(1) from users where created_at > now () - interval '4 weeks' group by 1; If you ran this query midweek, say on a Wednesday. Note there can be ambiguity in the months returned by age because different months have a different number of days. You can also use DROP TABLE command to delete complete table but it would remove complete table structure from the database and you would need to re-create this table once again if you wish to store some data. 9. 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. Table 9. This example uses TRUNC on a date to truncate it to a day. The date/time functions provide a powerful set of tools for manipulating various date/time types. Get difference between day just when the difference is positive. range_values as ( select date_trunc('month', current_date) as minval, ( date_trunc('day', current_date) + interval '1 day' - interval '1 second' ) as maxval from people )PostGreSQL : date_trunc() returns timestamp with timezone when used on date. The return value is of type timestamp with all fields that are less than. g. Syntax: date_trunc(text, timestamp) Return Type: timestamp. Return the relative rank of the current row. end_date) >= DATE_TRUNC ('day', q. date) going over the. 03. That means that TRUNCATE can be rolled back just like any other. field selects to which precision to truncate the time stamp value. 7. EXTRACT, date_part EXTRACT(field FROM source) The extract function retrieves subfields such as year or hour from date/time values. Truncate a date. In PostgreSQL, you can use the AGE () function to achieve these tasks. 1. 9. When used to aggregate data, it allows you to find time-based trends like daily purchases or messages per second. Simply try. In PostgreSQL, the DATE_PART () function is used to query for subfields from a date or time value. source must be a value expression of type timestamp, time, or interval. Dropping Partitions. 29 4 4 bronze badges. So, weeks always range in [0, 52]. 32 shows the available functions for date/time value processing, with details appearing in the following subsections. Below is the function. In the above output, it shows the output like a day of the timestamp value but we can find the week number. Part of AWS Collective. Date_Trunc varies parts of the date/time: century, year, month, day, hour, minute, second, millisecond,. 0. 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). 1 Answer. 8. When used to aggregate data, it allows you to find time-based trends like daily purchases or messages per second. You can use DATE_TRUNC along with TO_CHAR function. In the above output, it shows the output like a day of the timestamp value but we can find the. Either truncate the timestamp by minutes using date_trunc, which will return a timestamp without seconds, or use to_char if it is only about formatting the output: SELECT date_trunc ('minute',VISIT_DATE) FROM t; SELECT to_char (VISIT_DATE,'yyyy-mm-dd hh24:mi') FROM t; Demo: In Postgresql, to truncate or extract the week of the timestamp value, pass the week as a string to the date_trunc function. For formatting functions, refer to Section 9. 1. for example 2018-10-15 will be 2018-10-01 and 2018-10-30 also will be 2018-10-01. , date/time types) we describe the actual behavior in subsequent sections. 6. - The value for the field. Table 10-4. I see that date_trunc function returns timestamp and intervals cannot be cast to date type: select current_date -. ) field selects to which precision to truncate the input value. 3 Answers. 9. Truncate all the data in the table and just let the data of the last 6 months. For formatting functions, refer to Section 9. Replicate Oracle's `TRUNC(DATE, 'WW')` behaviour in PostgreSQL. SELECT id, date , date_trunc('quarter', date - interval '2 month') + interval '2 month' AS quarter FROM player_daily_score; db<>fiddle here. In PostgreSQL, the DATE_TRUNC () function trims unnecessary values from the date and time and returns a result with specific precision. It's bad practice but you might be forgiven if you use. POSTGRESQL Course Bundle - 5 Courses in 1 | 1 Mock Test. SELECT date_trunc ('week', day::DATE + 1)::date + 5 AS anchor, AVG (value) AS average FROM daily_metrics WHERE metric = 'daily-active-users' GROUP BY anchor ORDER BY anchor. I am using the following query to change all date to the Monday of the corresponding week: select date_trunc('week', join_date) as join_wk from my_table This query converts 2017-08-23 11:30:02 to 2017-08-21 00:00:00SELECT (date_trunc('MONTH', now())+'1 month'::interval - '1 day'::interval);. - The value for the “field” argument must be valid. Isolating hour-of-day and day-of-week with EXTRACT function. By default, Oracle TRUNC truncates a datetime to day (sets the zero time): Oracle:-- Get the current datetime with time set to zero SELECT TRUNC (SYSDATE) FROM dual; # 2013-02-11 00:00:00 SELECT TRUNC (SYSDATE, 'DD') FROM dual; # 2013-02-11 00:00:00. Don't forget to keep the timezone in mind. 000000 Expected: 1967-12-04 00:00:00. 15. For removing the data and preserving the table-structures in pgAdmin you can do: Right-click database -> backup, select "Schema only". Fungsi DATE_TRUNC. PostgreSQL: Return NULL values for dates that do not exist. I have a slow query that generates a report of account activity per week over the past year. Date/Time Functions and Operators. SELECT TO_CHAR (current_date, '"W"IW ')|| TO_CHAR (DATE_TRUNC ('week',current_date),'DD/MM - ')|| TO_CHAR (DATE_TRUNC ('week',current_date)+ INTERVAL '6 day','DD/MM') and change the added values within + INTERVAL 'c day' (in. 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. org> Reviewed-by: Isaac Morland <isaac. PostgreSQL Version: 9. Definition of PostgreSQL Trunc () PostgreSQL’s trunc () function is used to truncate the decimal places to a certain precision. date_trunc('field', source) source is a value expression of type timestamp (values of type date and time are cast automatically). The return type of the date_trunc function is a timestamp. See Section 13. We’ll use it for different. The DATE_TRUNC () function in Postgres truncate a date or time value to a specific precision. For formatting functions, refer to Section 9. May 2, 2016 at 21:56. SELECT date_trunc('week', date::date) AS "weekly&quo. PostgreSQL - Date Difference in Months. For formatting functions, refer to Section 9. Table 9. hot to add one month to the required column by substracting one day from it in postgresql. Truncation means setting specific parts of. How to write the query to get the first and last date of a January and other month's in postgresql 1 Get the timestamp of the last and first day of a month in postgresSQLExample 3: Truncate a TIME value to the beginning of the minute. Notes: it looks like you have numbers stored as text. It can also return a number truncated to the whole number if no precision is defined. For example, date_trunc can aggregate by one second, one hour,. Yeah. But, for some reasons, the length of the Month value is fixed to the longest month name available. 9. Because a TRUNCATE is DDL it involves two commits, one before and one after the statement execution. 31 shows the available functions for date/time value processing, with details appearing in the following subsections. 9. Expressing PostgreSQL timestamps without zones in local time. You can use the date_trunc function to achieve this: select date_trunc('second', time_captured) from server_perf;. 32 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. default_time_zone='+00:00'. select distinct datecalcul from Table where datecalcul > now () - INTERVAL '6 months' order by datecalcul asc. Now that our entity is all set up, let’s create a Spring Data repository to query those articles. CREATE INDEX ON. date_trunc. Mathematical operators are provided for many PostgreSQL types. I'm trying to truncate double precision value when I'm build json using json_build_object() function in PostgreSQL 11. Query the Entities. Assuming data type timestamp. ). Mathematical Functions and Operators. Oracle's DATE data type (which is what sysdate returns) always contains a time part which can not be removed. Finally, it returns the truncated part with a specific precision level. A general solution for any time interval can be based on the epoch value and integer division to truncate. If PostgreSQL supported RANGE in window functions this would be considerably simpler than it is. 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 in your queries. I edited my full query into my post now. PostgreSQL TRUNC() Function. SELECT TRUNC(10 / 3. Avoid this, if you can. The TRUNCATE TABLE statement removes all rows from a table. I am using PostreSQl server and have to get data grouped by date part of timestamp (ie. serpid = s. These SQL-standard functions all return values based on the start. PostgreSQL - subtract 'days' from a returned 'date' value without also returning timestamp. Hot Network Questions Detecting if a video mode is supported by INT 0x10PostgreSQL - DATE/TIME Functions and Operators. I need it to return april 22. 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. How to Exclude Current or Partial Weeks in PostgreSQL. 456,2) AS "Truncate upto 2 decimal"; Sample Output: Truncate upto 2 decimal ----- 67. There is nothing wrong with using date_trunc under the right circumstances. 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. However, Postgres' date type does I'm a little confused about using trunc() function in postgresql. postgres sql, date_trunc without extra zeroes. I will get the same. Right now. Follow. Use EXTRACT and the UNIX-Timestamp. Format date with to_char; Setup. 300 and 19:28:00. I want something in between like 100 milliseconds (1/10 second). Date_trunc (field (month, day, year) from timestamp) Example閾値として、0msecちょうどで更新日時を比較したい時にdate_truncを使用したので、その備忘録。 PostgreSQLで記述。 秒で指定した場合. 61 Avg. In the example below, we use the select operation on the stud_cmp table to retrieve data by comparing two dates using the date_trunc function. 24. An alternative pproach is to use to_char function. , hour, week, or month and returns the truncated timestamp or interval with a level of precision. EXTRACT, date_part EXTRACT(field FROM source)The extract function retrieves subfields such as year or hour from date/time values. CREATE OR REPLACE FUNCTION reset_Default () RETURNS VOID AS ' BEGIN TRUNCATE TABLE details; INSERT INTO details values ('car',2); INSERT INTO details values ('bus',4); RETURN; END; ' LANGUAGE 'plpgsql';. date_trunc ('day', yourtimestamp) will return a timesamp, but with hours, mins and secs to zero. 6. DATE_TRUNC () will return an interval. Delaying Execution. 2. See full list on database. The precision values are a subset of the field identifiers that can be used with the EXTRACT () and DATE_PART () functions. 0. postgresql query to return the day of the week of the first day of the month two years from today. For types without common mathematical conventions for all possible permutations (e. CREATE FUNCTION TRUNC ( dttm TIMESTAMP ) RETURNS TIMESTAMP AS $$ SELECT DATE_TRUNC('DAY',$1); $$ LANGUAGE SQL IMMUTABLE; select TRUNC(NOW()::timestamp); 12. AT TIME ZONE. The most convenient method to group table data is the DATE_TRUNC() function, which allows us to truncate a timestamp to a specific level of precision, such as the month, day, hour, etc. In PostgreSQL, DATE_TRUNC Function is used to truncate a timestamp type or interval type with specific and high level of precision. 0. 2) at or above day precision, the time zone offset is recalculated, according to the current TimeZone configuration. Finding events relative to the present time with NOW () and CURRENT_DATE functions. UPPER関数 大文字に変換する. Covers all your examples. Inspecting MCV Lists. The most frequently used Postgres date functions and business scenarios where they come in handy: Rounding off timestamps with DATE_TRUNC function. 5 for more details. thedate), r. Including the id column (assuming it's the PK) in GROUP BY is a noise operation, as nothing will be aggregated. MessageText: function date_trunc(unknown, timestamp with time zone, unknown) does not exist Hint: No function matches the given name and argument types. Postgres 11 adds essential functionality. WW truncates date to the nearest previous day same to the first day of week of the year. 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). datepart. If you want to know how many. 5. The basic syntax of the DATE_TRUNC function is as shown below: DATE_TRUNC(precision, source);. trunc() will set that to 00:00:00 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). It's not immutable because it depends on the sessions time zone setting. Below is the syntax of the TRUNCATE command:. 000000 Example 2: (This one works fine)Read: Postgresql date_trunc function Postgresql date add year. 31 illustrates the behaviors of the basic arithmetic operators ( +, *, etc. For example: SELECT user_id FROM user_logs WHERE login_date >= '2014-02-01' AND login_date < '2014-03-01'. (Values of type date and time. 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). This chapter describes most of them, although additional special-purpose functions appear in relevant sections of the manual. 9. date_trunc() in Postgres is the equivalent to trunc() for dates in Oracle - but it's not needed for date values in Postgres as a date does not contain a time part. The date part to which to truncate the timestamp value. 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. Nothing Round a timestamp to the nearest 5 minute mark. Its Java equivalent is: Instant. In Postgresql, we can also add a year to the current date using the INTERVAL data type. How to convert this string into timestamp in postgresql? Hot Network QuestionsThe PostgreSQL TRUNCATE TABLE command is used to delete complete data from an existing table. 2: date_trunc('hour', timestamp '2001-02-16 20:38:40') 2001-02-16 20:00:00:. start }}'::timestamp) The result of that is a timestamp from which you can subtract the interval:. 19, earlier I have made the following Query SELECT DATE_TRUNC ('minute', some_date) FROM some_table; This was working. You may create an overloaded TRUNC function in Postgresql. - It retrieves the trimmed part with a specific precision level. As far as I know, if I want to trunc date, I need to use the date_trunc() function in posgresql. For types without standard mathematical conventions (e. pdpn = conversion to double precision, then numeric (8,4) - 4 significant decimals kept, as wanted. Ignoring seconds from timestamp postgres. The result is 03 records. 9899999999999984 number to ONLY two decimals but making sure it DOES NOT round it to 20. Trimming trailing :00 from output after date_trunc. 1. 0. Day 1. But the week starts on Monday in Postgres by default. Here’s the current timestamp. PostgreSQL 错误：函数date_trunc（没有时区的时间戳）不存在 在本文中，我们将介绍 PostgreSQL 数据库中的一个常见错误：函数 date_trunc(timestamp without time zone) 不存在。我们将详细解释该错误的原因，并提供解决方法和示例说明。 阅读更多：PostgreSQL 教程 PostgreSQL 中的日期和时间函数 PostgreThe 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. 9. Four star feature compatibility Four star automation level Data Types PostgreSQL is using different function names. Checkout DoctrineExtensions. 5 for more details. Efficiently select beginning and end of multiple contiguous ranges in Postgresql query. trim the time out of the range. WHERE句でdate_trunc 関数：timestampの丸めを使ったせいで、インデックスを使ってくれなかった。 それはそうですね。関数一般を適用した結果は、値の順序が変わってしまう＝index上の位置が変わってしまう、可能性があるので。 対策：postgresql; truncate; Share. The following illustrates the syntax of the AGE () function: The AGE () function accepts two. 0. Author: John Naylor <john. To DELETE command will also delete all data from the table, but it may take more time if a table being deleted has a large amount of data. TRUNCATE quickly removes all rows from a set of tables. If you phrase your query as:Essentially, time_bucket() is a more powerful version of the standard PostgreSQL date_trunc() function. 94. You can now use date_trunc (text, timestamp) with Doctrine! Note: You can easily adapt this code for every additional Postgres/MySQL function. The PostgreSQL date_trunc() function truncates a specified timestamp or interval value to the specified part and returns the result. PostgreSQL 错误：函数date_trunc（没有时区的时间戳）不存在 在本文中，我们将介绍 PostgreSQL 数据库中的一个常见错误：函数 date_trunc(timestamp without time zone) 不存在。我们将详细解释该错误的原因，并提供解决方法和示例说明。 阅读更多：PostgreSQL 教程 PostgreSQL 中的日期和时间函数 PostgreThe 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. , are used to compare the dates in Postgres. Date and Time Functions are scalar functions that perform operations on temporal or numeric input and return temporal or numeric values. ) from a date, time, or timestamp value. e. trunc() will set that to 00:00:00. Weeks rolling up to months in SQL (date_trunc) 0. date_trunc('hour', timestamp '2001-02-16 20:38:40') → 2001-02-16 20:00:00:. 9. , table_z; Deleting content of named tables and tables that reference to them (I will explain it in more details later in this answer): TRUNCATE table_a, table_b. Functions and Operators. SELECT current_date + cast (abs (extract (dow FROM current_date) - 7) + 1 AS int); works, although there might be more elegant ways of doing it. 9. Introduction to PostgreSQL age () function. The release notes: Add all window function framing options specified by SQL:2011 (Oliver Ford, Tom Lane). The second one which use DATE_TRUNC will tranc any date to the first day of the month. date) AND DATE_TRUNC ('day', c. To generate a series of dates this is the optimal way: SELECT t. 8 but with no luck. orm: dql: datetime_functions: date_trunc: YOUR_BUNDLE_HEREDoctrineExtensionsDateTrunc. I'm a little confused about using trunc() function in postgresql. Caused by: org. postgresql:postgresql:9. ) This function takes two arguments. 4. This is an excerpt from my sql query. Jun 27, 2014. 9. Let's say you have a simple query that groups by week and looks back at the last 4 weeks: select date_trunc ('week', created_at), -- or hour, day, month, year count(1) from users where created_at > now () - interval '4 weeks' group by 1; If you ran this query midweek, say on a Wednesday. CREATE OR REPLACE FUNCTION round_time_10m(TIMESTAMP. 0. 03. PostgreSQL sequence of full weeks number between two dates. For example, if I have a table that looks like this. 1) below the day precision (first parameter) the time zone offset of the result is always the same as the second parameters' offset. I'm trying to create what should be a super simple line chart showing the avg annual. 9. Right-click the new database -> restore -> select the backup, select "Schema only". Notice a year has 365/7 = 52,142857142857143 weeks, or 366/7 = 52,285714285714286 weeks, depending on its length. jdbc. 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. To add a new column to a table in PostgreSQL, you can use the ALTER TABLE statement with the ADD COLUMN clause. A general solution for any time interval can be based on the epoch value and integer division to truncate. These can be extracted as follows (using today as the date): select extract (isoyear from current_date); select extract (week from current_date); But there. PostgreSQL -> SQLite: DATE_TRUNC Equivalent. EXTRACT. The exceptions are the MONTHS_BETWEEN function, which returns a number, and the ROUND and TRUNC functions, which do not accept timestamp or interval values at all. I have tried using function date_trunc('day', d_date::timestamp) but I get that is always staying in the same day. 152488 secs1. Here’s the current timestamp. We are using date_trunc, group by, and aggregate functions to retrieve. timestamp)) from rollup_days as rp; To convert the timestamp back to a bigint, use extract ()Mathematical operators are provided for many PostgreSQL types. PostgreSQL's approach uses the month from the earlier of the. You should be familiar with the background information on date/time data types from. 2. How to use the PostgreSQL Date Function: Date_Trunc. DATE_TRUNC('datepart', timestamp) Pendapat. 1. To remove all data from a table, you use the DELETE statement. SELECT date_trunc ('month', cast (my_date as timestamp)) FROM my_table. The PostgreSQL date_trunc rolls up the date to the first instance of the date depending upon the granularity ( day, week, month, etc. These SQL-standard functions all return values based on the start. 98 . 1 Truncate a date in Postgres (latest version) 0 PL/PGSQL function - passing a TEXT argument to date_trunc() 0 custom DATE_TRUNC timeframes. Mathematical operators are provided for many PostgreSQL types.