SPARK-SQL内置函数之时间日期类

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一、获取当前时间

1.current_date获取当前日期

2018-04-09

2.current_timestamp/now()获取当前时间

2018-04-09 15:20:49.247

二、从日期时间中提取字段 

1.year,month,day/dayofmonth,hour,minute,second

Examples:> SELECT day(\'2009-07-30\'); 30

2.dayofweek (1 = Sunday, 2 = Monday, ..., 7 = Saturday),dayofyear

Examples:> SELECT dayofweek(\'2009-07-30\');　　 5

Since: 2.3.0

3.weekofyear

weekofyear(date) - Returns the week of the year of the given date. A week is considered to start on a Monday and week 1 is the first week with >3 days.

Examples:> SELECT weekofyear(\'2008-02-20\');　　 8

4.trunc截取某部分的日期，其他部分默认为01

第二个参数 ["year", "yyyy", "yy", "mon", "month", "mm"]

Examples:

> SELECT trunc(\'2009-02-12\', \'MM\');
 2009-02-01
> SELECT trunc(\'2015-10-27\', \'YEAR\');
 2015-01-01

5.date_trunc ["YEAR", "YYYY", "YY", "MON", "MONTH", "MM", "DAY", "DD", "HOUR", "MINUTE", "SECOND", "WEEK", "QUARTER"]

Examples:> SELECT date_trunc(\'2015-03-05T09:32:05.359\', \'HOUR\');　　2015-03-05T09:00:00

Since: 2.3.0

6.date_format将时间转化为某种格式的字符串

Examples:> SELECT date_format(\'2016-04-08\', \'y\');　　　　2016

三、日期时间转换

1.unix_timestamp返回当前时间的unix时间戳

Examples:

> SELECT unix_timestamp();　　1476884637
> SELECT unix_timestamp(\'2016-04-08\', \'yyyy-MM-dd\');　　 1460041200

2.from_unixtime将时间戳换算成当前时间，to_unix_timestamp将时间转化为时间戳

Examples:

> SELECT from_unixtime(0, \'yyyy-MM-dd HH:mm:ss\');　　1970-01-01 00:00:00
>SELECT to_unix_timestamp(\'2016-04-08\', \'yyyy-MM-dd\');　　1460041200

3.to_date/date将字符串转化为日期格式，to_timestamp（Since: 2.2.0）

> SELECT to_date(\'2009-07-30 04:17:52\');　　2009-07-30
> SELECT to_date(\'2016-12-31\', \'yyyy-MM-dd\');　　 2016-12-31

> SELECT to_timestamp(\'2016-12-31 00:12:00\');　　 2016-12-31 00:12:00

4.quarter 将1年4等分(range 1 to 4)

Examples:> SELECT quarter(\'2016-08-31\');  3

四、日期、时间计算

1.months_between两个日期之间的月数

months_between(timestamp1, timestamp2) - Returns number of months between timestamp1 and timestamp2.

Examples:> SELECT months_between(\'1997-02-28 10:30:00\', \'1996-10-30\');　　3.94959677

2. add_months返回日期后n个月后的日期

Examples:> SELECT add_months(\'2016-08-31\', 1);　　2016-09-30

3.last_day(date),next_day(start_date, day_of_week)

Examples:

> SELECT last_day(\'2009-01-12\');　　2009-01-31

> SELECT next_day(\'2015-01-14\', \'TU\');　　2015-01-20

4.date_add,date_sub(减)

date_add(start_date, num_days) - Returns the date that is num_days after start_date.

Examples:

> SELECT date_add(\'2016-07-30\', 1);　　2016-07-31

5.datediff（两个日期间的天数）

datediff(endDate, startDate) - Returns the number of days from startDate to endDate.

Examples:> SELECT datediff(\'2009-07-31\', \'2009-07-30\'); 1

6.关于UTC时间

to_utc_timestamp

to_utc_timestamp(timestamp, timezone) - Given a timestamp like \'2017-07-14 02:40:00.0\', interprets it as a time in the given time zone, and renders that time as a timestamp in UTC. For example, \'GMT+1\' would yield \'2017-07-14 01:40:00.0\'.

Examples:> SELECT to_utc_timestamp(\'2016-08-31\', \'Asia/Seoul\');　　2016-08-30 15:00:0

from_utc_timestamp

from_utc_timestamp(timestamp, timezone) - Given a timestamp like \'2017-07-14 02:40:00.0\', interprets it as a time in UTC, and renders that time as a timestamp in the given time zone. For example, \'GMT+1\' would yield \'2017-07-14 03:40:00.0\'.

Examples:> SELECT from_utc_timestamp(\'2016-08-31\', \'Asia/Seoul\');　　2016-08-31 09:00:00