Hive版本: hive-1.1.0-cdh5.14.2
1. Unix時間戳轉日期：from_unixtime
語法：from_unixtime(bigint unixtime[, string format])
返回值：string
描述: Unix時間戳轉換爲日期格式
0: jdbc:hive2://node03:10000> select from_unixtime(1237573801, 'yyyy-MM-dd HH:mm:ss') as time_string;
+----------------------+--+
| time_string |
+----------------------+--+
| 2009-03-21 02:30:01 |
+----------------------+--+
1 row selected (0.14 seconds)
0: jdbc:hive2://node03:10000> select from_unixtime(1237573801) as time;
+----------------------+--+
| time |
+----------------------+--+
| 2009-03-21 02:30:01 |
+----------------------+--+
1 row selected (0.126 seconds)2. 當前Unix時間戳：unix_timestamp
語法：unix_timestamp()
返回值: bigint
描述：返回當前時間的Unix時間戳
0: jdbc:hive2://node03:10000> select unix_timestamp() as current_time;
+---------------+--+
| current_time |
+---------------+--+
| 1592639728 |
+---------------+--+3. 日期轉Unix時間戳：unix_timestamp
語法: unix_timestamp(string date)
返回值: bigint
描述：返回指定日期的Unix時間戳
0: jdbc:hive2://node03:10000> select unix_timestamp('2009-03-20 11:30:01') as time_in_seconds;
+------------------+--+
| time_in_seconds |
+------------------+--+
| 1237519801 |
+------------------+--+
1 row selected (0.138 seconds)4. 指定日期某部分轉爲Unix時間戳：unix_timestamp
語法：unix_timestamp(string date, string pattern)
返回值: bigint
描述：根據指定的pattern，轉換日期爲Unix時間戳
0: jdbc:hive2://node03:10000> select unix_timestamp('2009-03-20', 'yyyy-MM-dd') as time_in_seconds;
+------------------+--+
| time_in_seconds |
+------------------+--+
| 1237478400 |
+------------------+--+
1 row selected (0.121 seconds)5. 時間戳轉日期：to_date
語法：to_date(string timestamp)
返回值: 2.1.0版本前返回string，2.1.0版本後返回date
描述: 把指定的時間戳轉換爲日期格式
0: jdbc:hive2://node03:10000> select to_date("1970-01-01 00:00:00") as date1;
+-------------+--+
| date1 |
+-------------+--+
| 1970-01-01 |
+-------------+--+
1 row selected (0.141 seconds)6. 提取日期中的年份：year
語法：year(string date)
返回值：int
描述：提取日期中的年份部分
0: jdbc:hive2://node03:10000> select year('2020-06-20 16:01:00') as year;
+-------+--+
| year |
+-------+--+
| 2020 |
+-------+--+
1 row selected (0.116 seconds)
0: jdbc:hive2://node03:10000> select year('2020-06-20') as year;
+-------+--+
| year |
+-------+--+
| 2020 |
+-------+--+
1 row selected (0.119 seconds)7. 提取日期中的月份：month
語法：month(string date)
返回值: int
描述：提取日期中的月份部分
0: jdbc:hive2://node03:10000> select month('2020-06-20') as month;
+--------+--+
| month |
+--------+--+
| 6 |
+--------+--+
1 row selected (0.127 seconds)
0: jdbc:hive2://node03:10000> select month('2020-06-20 16:08:00') as month;
+--------+--+
| month |
+--------+--+
| 6 |
+--------+--+
1 row selected (0.112 seconds)8. 提取日期中的日：day
語法: day(string date) 、dayofmonth(date)
返回值: int
描述：提取日期中的日部分
0: jdbc:hive2://node03:10000> select day('2020-06-20') as day;
+------+--+
| day |
+------+--+
| 20 |
+------+--+
1 row selected (0.189 seconds)
0: jdbc:hive2://node03:10000> select dayofmonth('2020-06-20') as day;
+------+--+
| day |
+------+--+
| 20 |
+------+--+
1 row selected (0.106 seconds)9. 提取日期中的小時：hour
語法：hour(string date)
返回值：int
描述：提取日期中的小時部分
0: jdbc:hive2://node03:10000> select hour('2020-06-20 16:08:00') as hour;
+-------+--+
| hour |
+-------+--+
| 16 |
+-------+--+
1 row selected (0.113 seconds)
0: jdbc:hive2://node03:10000> select hour('16:08:00') as hour;
+-------+--+
| hour |
+-------+--+
| 16 |
+-------+--+10. 提取日期中的分鐘/秒：minute/second
語法：minute(string date) / second(string date)
返回值: int
描述：提取日期中的分鐘/秒部分
0: jdbc:hive2://node03:10000> select hour('2020-06-20 16:08:00') as hour,
. . . . . . . . . . . . . . > minute('2020-06-20 16:08:00') as monute,
. . . . . . . . . . . . . . > second('2020-06-20 16:08:00') as second
. . . . . . . . . . . . . . > ;
+-------+---------+---------+--+
| hour | monute | second |
+-------+---------+---------+--+
| 16 | 8 | 0 |
+-------+---------+---------+--+11. 返回日期處於當年的第幾周：weekofyear
語法：weekofyear(string date)
返回值：int
描述: 返回指定日期處於當年的第幾周
0: jdbc:hive2://node03:10000> select weekofyear('2020-06-20') as weekofyear;
+-------------+--+
| weekofyear |
+-------------+--+
| 25 |
+-------------+--+
1 row selected (0.139 seconds)12. 兩日期間隔天數：datediff
語法：datediff(string enddate, string startdate)
返回值: int
描述: 返回兩指定日期之間的天數
0: jdbc:hive2://node03:10000> select datediff('2020-06-20', '2020-06-15') as days;
+-------+--+
| days |
+-------+--+
| 5 |
+-------+--+
1 row selected (0.138 seconds)13. 日期增加函數: dateadd
語法：date_add(date/timestamp/string startdate, tinyint/smallint/int days)
返回值: 2.1.0版本前返回string，2.1.0版本後返回date
描述：返回開始日期startdate增加天數days後的日期
0: jdbc:hive2://node03:10000> select date_add('2020-06-15', 5) as date;
+-------------+--+
| date |
+-------------+--+
| 2020-06-20 |
+-------------+--+
1 row selected (0.14 seconds)14. 日期減少函數: datesub
語法: date_sub(date/timestamp/string startdate, tinyint/smallint/int days)
返回值: 2.1.0版本前返回string，2.1.0版本後返回date
描述: 返回開始日期startdate減少天數days後的日期
0: jdbc:hive2://node03:10000> select date_sub('2020-06-20', 5) as date;
+-------------+--+
| date |
+-------------+--+
| 2020-06-15 |
+-------------+--+
1 row selected (0.128 seconds)15. 當前日期/當前時間戳：current_date / current_timestamp
語法: current_date / current_timestamp
返回值：date / timestamp
描述: 返回當前日期或者時間戳
0: jdbc:hive2://node03:10000> select current_date as date, current_timestamp as timestamp;
+-------------+--------------------------+--+
| date | timestamp |
+-------------+--------------------------+--+
| 2020-06-20 | 2020-06-20 18:19:35.736 |
+-------------+--------------------------+--+
1 row selected (0.145 seconds)16. 月份增加函數：add_months
語法: add_months(string start_date, int num_months, output_date_format)
返回值: string
描述: 返回開始日期start_date增加num_months月後的日期，output_date_format做爲可選參數只在Hive 4.0.0版本後可用。
0: jdbc:hive2://node03:10000> select add_months('2020-06-30', 1) as add_months;
+-------------+--+
| add_months |
+-------------+--+
| 2020-07-31 |
+-------------+--+
1 row selected (0.138 seconds)17. 當月最後一天：last_day
語法：last_day(string date)
返回值: string
描述: 返回指定日期所在月份的最後一天
0: jdbc:hive2://node03:10000> select last_day(current_date) as last_day;
+-------------+--+
| last_day |
+-------------+--+
| 2020-06-30 |
+-------------+--+
1 row selected (0.117 seconds)
0: jdbc:hive2://node03:10000> select last_day(current_timestamp) as last_day;
+-------------+--+
| last_day |
+-------------+--+
| 2020-06-30 |
+-------------+--+
1 row selected (0.105 seconds)18. 下一個周幾的日期：next_day
語法: next_day(string start_date, string day_of_week)
返回值: string
描述: 返回開始日期start_date後的第一個周幾(如週一)的日期，其中day_of_week可以爲星期的2或3位縮寫如：Mo, tue，也可以是星期的全拼，如：FRIDAY
0: jdbc:hive2://node03:10000> select next_day('2020-06-20', 'MON') as next_monday;
+--------------+--+
| next_monday |
+--------------+--+
| 2020-06-22 |
+--------------+--+
1 row selected (0.16 seconds)19. 截斷日期：trunc
語法：trunc(string date, string format)
返回值: string
描述：按指定格式截斷日期，format可以爲月或年：MONTH/MON/MM, YEAR/YYYY/YY
0: jdbc:hive2://node03:10000> select trunc('2020-06-20', 'MM') as trunc_mon;
+-------------+--+
| trunc_mon |
+-------------+--+
| 2020-06-01 |
+-------------+--+
1 row selected (0.133 seconds)
0: jdbc:hive2://node03:10000> select trunc('2020-06-20', 'YEAR') as trunc_date;
+-------------+--+
| trunc_date |
+-------------+--+
| 2020-01-01 |
+-------------+--+
1 row selected (0.164 seconds)20. 計算間隔月份：months_between
語法：months_between(date1, date2)
返回值: double
描述: 返回兩日期的間隔月份，精度到小數點後最多8位
0: jdbc:hive2://node03:10000> select months_between('2020-06-20','2020-06-01') as months_between1,
. . . . . . . . . . . . . . > months_between('2020-06-20','2020-06-20') as months_between2,
. . . . . . . . . . . . . . > months_between('2020-06-20','2020-05-20') as months_between3,
. . . . . . . . . . . . . . > months_between('2020-06-20','2020-07-20') as months_between4;
+------------------+------------------+------------------+------------------+--+
| months_between1 | months_between2 | months_between3 | months_between4 |
+------------------+------------------+------------------+------------------+--+
| 0.61290323 | 0.0 | 1.0 | -1.0 |
+------------------+------------------+------------------+------------------+--+
1 row selected (0.127 seconds)