获取当前时间截:
1 select unix_timestamp() ;
2 +-------------+--+
3 | _c0 |
4 +-------------+--+
5 | 1521684090 |
6 +-------------+--+
获取当前时间1：
1
select current_timestamp;
2 +--------------------------+--+
3 | _c0 |
4 +--------------------------+--+
5 | 2018-03-22 10:04:02.568 |
6 +--------------------------+--+
获取当前时间2：
1 SELECT from_unixtime(unix_timestamp());
2 +----------------------+--+
3 | _c0 |
4 +----------------------+--+
5 | 2018-03-22 10:04:38 |
6 +----------------------+--+
获取当前日期：
1 SELECT CURRENT_DATE;
2 +-------------+--+
3 | _c0 |
4 +-------------+--+
5 | 2018-03-22 |
6 +-------------+--+
日期差值：
datediff(结束日期，开始日期)，返回结束日期减去开始日期的天数。
1 select datediff(CURRENT_DATE,'2017-01-01') as datediff;
2 +-----------+--+
3 | datediff |
4 +-----------+--+
5 | 445 |
6 +-----------+--+
日期加减
：date_add（时间，增加天数），返回值为时间天+增加天的日期；date_sub（时间，减少天数），返回日期减少天后的日期。
1 select date_add(current_date,365) as dateadd;
2 +-------------+--+
3 | dateadd |
4 +-------------+--+
5 | 2019-03-22 |
6 +-------------+--+
时间差：两个日期之间的小时差
1 select (hour('2018-02-27 10:00:00')-hour('2018-02-25 12:00:00')+(datediff('2018-02-27 10:00:00','2018-02-25 12:00:00'))*24) as hour_subValue;
2 +----------------+--+
3 | hour_subValue |
4 +----------------+--+
5 | 46 |
6 +----------------+--+
获取年、月、日、小时、分钟、秒、当年第几周
1 select
2 year('2018-02-27 10:00:00') as year
3 ,month('2018-02-27 10:00:00') as month
4 ,day('2018-02-27 10:00:00') as day
5 ,hour('2018-02-27 10:00:00') as hour
6 ,minute('2018-02-27 10:00:00') as minute
7 ,second('2018-02-27 10:00:00') as second
8 ,weekofyear('2018-02-27 10:00:00') as weekofyear
10 +-------+--------+------+-------+---------+---------+-------------+--+
11 | year | month | day | hour | minute | second | weekofyear |
12 +-------+--------+------+-------+---------+---------+-------------+--+
13 | 2018 | 2 | 27 | 10 | 0 | 0 | 9 |
14 +-------+--------+------+-------+---------+---------+-------------+--+
转成日期：
1 select to_date('2018-02-27 10:03:01') ;
2 +-------------+--+
3 | _c0 |
4 +-------------+--+
5 | 2018-02-27 |
6 +-------------+--+
当月最后一天：
1 select last_day('2018-02-27 10:03:01');
2 +-------------+--+
3 | _c0 |
4 +-------------+--+
5 | 2018
-02-28 |
6 +-------------+--+
当月第一天：
1 select trunc(current_date,'MM') as day;
2 +-------------+--+
3 | day |
4 +-------------+--+
5 | 2018-03-01 |
6 +-------------+--+
当年第一天：
1 select trunc(current_date,'YY') as day;
2 +-------------+--+
3 | day |
4 +-------------+--+
5 | 2018-01-01 |
6 +-------------+--+
next_day
，
返回当前时间的下一个星期几所对应的日期
1 select next_day('2018-02-27 10:03:01', 'TU');
2 +-------------+--+
3 | _c0 |
4 +-------------+--+
5 | 2018-03-06 |
6 +-------------+--+
-- hive中怎么获取两个日期相减后的小时（精确到两位小数点），而且这两个日期有可能会出现一个日期有时分秒，一个日期没有时分秒的情况
select
t3.day1
,t3.day2
,t3.day -- 日期
,t3.hour -- 小时
,t3.min -- 分钟
,t3.day + t3.hour as hour_diff_1
,t3.day + t3.hour + t3.min as hour_diff_2
,round((cast(cast(t3.day1 as timestamp) as bigint) - cast(cast(t3.day2 as timestamp) as bigint)) / 3600,2) as hour_diff_3 -- 最优
,(datediff(t3.day1,t3.day2) * 24) + (nvl(hour(t3.day1),0) - nvl(hour(t3.day2),0)) + round((nvl(minute(t3.day1),0) - nvl(minute(t3.day2),0)) / 60,2) as hour_diff_4
from (
select
t2.day1
,t2.day2
,(datediff(t2.day1,t2.day2) * 24) as day -- 日期
,(hour(t2.day1) - hour(t2.day2)) as hour -- 小时
,round((minute(t2.day1) - minute(t2.day2)) / 60,2) as min -- 分钟
from (
select
cast(t1.day1 as timestamp) as day1
,cast(t1.day2 as timestamp) as day2
from (
select '2018-01-03 02:30:00' as day1, '2018-01-02 23:00:00' as day2 union all
select '2018-06-02 08:15:22' as day1, '2018-06-02 06:11:16' as day2 union all
select '2018-07-04' as day1, '2018-07-02 01:01:01' as day2
+------------------------+------------------------+------+-------+--------+--------------+--------------+--------------+--------------+--+
| day1 | day2 | day | hour | min | hour_diff_1 | hour_diff_2 | hour_diff_3 | hour_diff_4 |
+------------------------+------------------------+------+-------+--------+--------------+--------------+--------------+--------------+--+
| 2018-07-04 00:00:00.0 | 2018-07-02 01:01:01.0 | 48 | -1 | -0.02 | 47 | 46.98 | 46.98 | 46.98 |
| 2018-01-03 02:30:00.0 | 2018-01-02 23:00:00.0 | 24 | -21 | 0.5 | 3 | 3.5 | 3.5 | 3.5 |
| 2018-06-02 08:15:22.0 | 2018-06-02 06:11:16.0 | 0 | 2 | 0.07 | 2 | 2.07 | 2.07 | 2.07 |
+------------------------+------------------------+------+-------+--------+--------------+--------------+--------------+--------------+--+
### 当周第一天，最后一天
date -d "2018-10-24 $(($(date -d 2018-10-24 +%u)-1)) days ago" +%Y-%m-%d
date -d "2018-10-24 $((7-$(date -d 2018-10-24 +%u))) days" +%Y-%m-%d
