(1) 取当前时间:select now() (2) 取当前时间的日期: select current_date (3) 取当前具体时间(不含日期) select current_time 时间的加减: Select now() (1) 取三天后的时间:select now() + interval ‘3 day’; (2) 取三天前的时间:select now() - interval ‘3 day’ (3) 取1小时后(前)...
3. EXTRACT,date_part函数支持的field: 域 描述 例子 结果 CENTURY 世纪 EXTRACT(CENTURY FROM TIMESTAMP '2000-12-16 12:21:13'); 20 DAY (月分)里的日期域(1-31) EXTRACT(DAY from TIMESTAMP '2001-02-16 20:38:40'); 16 DECADE 年份域除以10 EXTRACT(DECADE from TIMESTAMP '2001-02-16 20:38...
select TO_CHAR((DATE_TRUNC('MONTH', to_date('20230307','YYYYMMDD')) + INTERVAL '-1 MONTH')::DATE,'YYYYMM') AS "LAST_MONTH", TO_CHAR((DATE_TRUNC('MONTH', to_date('20230307','YYYYMMDD')) + INTERVAL '-1 MONTH')::DATE,'YYYYMMDD') AS "LASST_MONTH_FIRST_DAY", TO_CHAR((DATE_...
格式∶LAST_DAY(date) TRUNC---将日期按照format格式截短,缺省为DD(不是四舍五入) 格式:TRUNC(date, format) 例∶ TRUNC (to_date(‘2002-11-07’,’yyyy-mm-dd’),’MM’)= 2002-11-01 4)分组函数 返回基于多个行的单一结果. 常用函数: AVG---求平均值 COUNT---返回查询的行数 MAX---返回查询...
使用日期函数:PostgreSQL提供了许多日期函数,可以用于处理日期数据。例如,可以使用"date_trunc"函数将日期截断到指定的精度,然后使用比较运算符筛选出介于两个日期之间的数据。以下是一个示例查询: 代码语言:txt 复制 SELECT * FROM table_name WHERE date_trunc('day', date_column) >= 'start_date' AND dat...
EXTRACT(type FROM date) data是日期,也可以是时间间距类型interval。这里的type需要指定为以下的值之一: 1 2 3 4 5 6 7 8 9 10 11 select now(); --2021-03-30 17:21:50 select extract(day from(now())); --30 select extract(month from(now())); --3 select extract(year from(now()))...
SELECTdate_trunc('day',hpdr.test_time)AS"day",count(*)AS"sum_count"FROMhealth_patient_device_result hpdrWHEREhpdr.test_time>now()-interval'3 months'GROUPBY1ORDERBY1; 2. 按周分组 SELECTdate_trunc('week',loggedin)AS"Week",count(*)AS"No. of users"FROMloginsWHEREcreated>now()-interval...
CREATE OR REPLACE FUNCTION get_monday_of_week(input_timestamp TIMESTAMP) RETURNS DATE AS $$ BEGIN RETURN (input_timestamp - INTERVAL '1' DAY * EXTRACT(DOW FROM input_timestamp))::date; END; $$ LANGUAGE plpgsql; 我们可以像这样调用这个函数: ...
Example 2: Subtract One Day From the Current Date The below statement shows how to subtract a day from today’s date: SELECT CURRENT_DATE - 1; In the above snippet, the CURRENT_DATE is used to get today’s date, while “1” represents the number of days to be subtracted from the cu...
FROM cnic; This way, you can add any particular day(s) to a date field in Postgres. Conclusion Postgres allows us to add a certain number of days to a date field using the plus “+” operator. In other databases like SQL Server, MySQL, etc., a built-in function named DATEADD() is...