postgreSql——时区问题

timestamptz、timestamp

SELECT ts AT TIME ZONE 'UTC'
FROM  (
   VALUES
      (timestamptz '2012-03-05 17:00:00+0')
    , (timestamptz '2012-03-05 18:00:00+1')
    , (timestamp   '2012-03-05 18:00:00+1')  -- ① loaded footgun!
    , (timestamp   '2012-03-05 11:00:00'  AT TIME ZONE '+6')
    , (timestamp   '2012-03-05 17:00:00'  AT TIME ZONE 'UTC')
    , (timestamp   '2012-03-05 07:00:00'  AT TIME ZONE 'US/Hawaii')  -- ②
    , (timestamp   '2012-03-05 07:00:00'  AT TIME ZONE 'HST')  -- ②
      ) t(ts);

 SELECT timestamptz '2012-03-05 20:00+03',
	timestamp '2012-03-05 17:00:00' AT TIME ZONE 'UTC',
	timestamp '2012-03-05 17:00:00' AT TIME ZONE 'UTC' AT TIME ZONE 'UTC'

　　

　　

查看现在距1970-01-01 00:00:00 UTC 的秒数

select extract(epoch from now());

select timestamp without time zone 'epoch',timestamp without time zone 'epoch' + 3600*interval '1 sec'

select timestamp without time zone 'epoch',timestamp with time zone 'epoch'

　　

　　

　

把epoch 值转换回时间戳

select timestamp without time zone 'epoch',timestamp with time zone 'epoch' ,timestamp 'epoch',timestamptz 'epoch'

　　

PostgreSQL的时间/日期函数使用

postgreSQL格式化时间的函数详解

mysql转为postgesql

SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(UTC_TIMESTAMP()) + tz.gmt_offset, '%a, %d %b %Y, %H:%i:%s') AS local_time
FROM  "Dict"."TimeZoneDetail" tz JOIN  "Dict"."TimeZoneToCountry" z
ON tz.zone_id=z.zone_id
WHERE tz.time_start <= UNIX_TIMESTAMP(UTC_TIMESTAMP()) AND z.zone_name='America/Los_Angeles'
ORDER BY tz.time_start DESC LIMIT 1;

SELECT (now() AT TIME ZONE 'UTC' )+interval '1'* tz."GMTOffset" AS local_time,now() as now,now() AT TIME ZONE 'UTC' as utcnow,tz."GMTOffset" as offsett
FROM  "Dict"."TimeZoneDetail" tz inner JOIN  "Dict"."TimeZoneToCountry" z
ON tz."ZoneId"=z."ZoneId"
WHERE to_timestamp(tz."TimeStart") <= timestamp 'epoch' AND z."ZoneName"='America/Los_Angeles'
ORDER BY tz."TimeStart" DESC LIMIT 1;

　　

函数	返回类型	描述	示例	结果
age(timestamp, timestamp)	interval	计算两个时间戳的时间间隔	select age(timestamp '2001-04-10', timestamp '1957-06-13');	43 years 9 mons 27 days
age(timestamp)	interval	计算current_date与入参时间戳的时间间隔	select age(timestamp '2016-07-07 12:00:00');	12:00:00
clock_timestamp()	timestamp with time zone	当前时间戳（语句执行时变化）	select clock_timestamp();	2016-07-08 15:14:04.197732-07
current_date	date	当前日期	select current_date;	2016-07-08
current_time	time with time zone	当前时间	select current_time;	15:15:56.394651-07
current_timestamp	timestamp with time zone	当前时间戳	select current_timestamp;	2016-07-08 15:16:50.485864-07
date_part(text, timestamp)	double precision	获取时间戳中的某个子域，其中text可以为year,month,day,hour,minute,second等	select date_part('year',timestamp'2016-07-08 12:05:06'), date_part('month',timestamp'2016-07-08 12:05:06'), date_part('day',timestamp'2016-07-08 12:05:06'), date_part('hour',timestamp'2016-07-08 12:05:06'), date_part('minute',timestamp'2016-07-08 12:05:06'), date_part('second',timestamp'2016-07-08 12:05:06');	2016 | 7 | 8 | 12 | 5 | 6
date_part(text, interval)	double precision	功能同上，只是第二个入参为时间间隔	select date_part('hour',interval'1 day 13:00:12');	13
date_trunc(text, timestamp)	timestamp	将时间戳截断成指定的精度， 指定精度后面的子域用0补充	select date_trunc('hour', timestamp'2016-07-08 22:30:33');	2016-07-08 22:00:00
date_trunc(text, interval)	interval	功能同上，只是第二个入参为时间间隔	select date_trunc('hour',interval'1 year 2 mon 3 day 22:30:33');	1 year 2 mons 3 days 22:00:00
extract(field from timestamp)	double precision	功能同date_part(text, timestamp)	select extract(hour from timestamp'2016-07-08 22:30:29');	22
extract(field from interval)	double precision	功能同date_part(text, interval)	select extract(hour from interval'1 day 13:00:12');	13
isfinite(date)	boolean	测试是否为有穷日期	select isfinite(date'2016-07-08'),isfinite(date'infinity');	t,f
isfinite(timestamp)	boolean	测试是否为有穷时间戳	select isfinite(timestamp'2016-07-08');	t
isfinite(interval)	boolean	测试是否为有穷时间间隔	select isfinite(interval'1day 23:02:12');	t
justify_days(interval)	interval	按照每月30天调整时间间隔	select justify_days(interval'1year 45days 23:00:00');	1 year 1 mon 15 days 23:00:00
justify_hours(interval)	interval	按照每天24小时调整时间间隔	select justify_hours(interval'1year 45days 343hour');	1 year 59 days 07:00:00
justify_interval(interval)	interval	同时使用justify_days(interval)和justify_hours(interval)	select justify_interval(interval'1year 45days 343hour');	1 year 1 mon 29 days 07:00:00
localtime	time	当日时间	select localtime;	15:45:18.892224
localtimestamp	timestamp	当日日期和时间	select localtimestamp;	2016-07-08 15:46:55.181583
make_date(year int, month int, day int)	date	创建一个日期	select make_date(2016,7,8);	2016-07-08
make_interval( years int DEFAULT 0, months int DEFAULT 0, weeks int DEFAULT 0, days int DEFAULT 0, hours int DEFAULT 0, mins int DEFAULT 0, secs double precision DEFAULT 0.0)	interval	创建一个时间间隔	select make_interval(1,hours=>3);	1 year 03:00:00
make_time( hour int, min int, sec double precision)	time	创建一个时间	select make_time(9,21,23);	09:21:23
make_timestamp( year int, month int, day int, hour int, min int, sec double precision)	timestamp	创建一个时间戳	select make_timestamp(2016,7,8,22,55,23.5);	2016-07-08 22:55:23.5
make_timestamptz(year int, month int, day int, hour int, min int, sec double precision, [ timezone text ])	timestamp with time zone	创建一个带有时区的时间戳	select make_timestamptz(2016,7,8,22,55,23.5);	2016-07-08 22:55:23.5-07
now()	timestamp with time zone	当前日期和时间	select now();	2016-07-08 15:55:30.873537-07
statement_timestamp()	timestamp with time zone	同now()	select statement_timestamp();	2016-07-08 15:56:07.259956-07
timeofday()	text	当前日期和时间，包含周几， 功能与clock_timestamp()类似	select timeofday();	Fri Jul 08 15:57:51.277239 2016 PDT
transaction_timestamp()	timestamp with time zone	事务开始时的时间戳	select transaction_timestamp();	2016-07-08 16:01:25.007153-07
to_timestamp(double precision)	timestamp with time zone	Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to timestamp	select to_timestamp(1284352323);	2010-09-12 21:32:03-07
pg_sleep(seconds double precision);		当前会话休眠seconds秒	select pg_sleep(5);
pg_sleep_for(interval)		当前会话休眠多长时间的间隔	select pg_sleep_for('5 seconds');
pg_sleep_until(timestamp with time zone)		当前会话休眠至什么时间点	select pg_sleep_until('2016-07-08 23:59:59');