轉載請註明轉自：http://www.cnblogs.com/feiyumo/p/8760846.html

一、獲取當前時間

1.current_date獲取當前日期

2018-04-09

2.current_timestamp/now()獲取當前時間

2018-04-09 15:20:49.247

二、從日期時間中提取欄位

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');　　

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擷取某部分的日期，其他部分預設為01

第二個引數 ["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將時間轉化為某種格式的字串

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

三、日期時間轉換

1.unix_timestamp返回當前時間的unix時間戳

Examples:

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

2.from_unixtime將時間戳換算成當前時間，to_unix_timestamp將時間轉化為時間戳

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將字串轉化為日期格式，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將1年4等分(range 1 to 4)

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

四、日期、時間計算

1.months_between兩個日期之間的月數

months_between(timestamp1, timestamp2) - Returns number of months betweentimestamp1andtimestamp2.

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

2. add_months返回日期後n個月後的日期

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(減)

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

Examples:

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

5.datediff（兩個日期間的天數）

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

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

6.關於UTC時間

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');　　2016-08-3015:00:0

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');　　2016-08-3109:00:00

轉自https://www.cnblogs.com/feiyumo/p/8760846.html