Hive常用函数（日期函数，取整函数，字符串操作函数，集合操作函数）
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常用函数
常用日期函数
unix_timestamp:返回当前或指定时间的时间戳
select unix_timestamp();
+-------------+
| _c0 |
+-------------+
| 1650871673 |
+-------------+
select unix_timestamp('2022-04-25','yyyy-MM-dd');
+-------------+
| _c0 |
+-------------+
| 1650844800 |
+-------------+
from_unixtime：将时间戳转为日期格式
select from_unixtime(1650844800);
+----------------------+
| _c0 |
+----------------------+
| 2022-04-25 00:00:00 |
+----------------------+
current_date：当前日期
select current_date;
+-------------+
| _c0 |
+-------------+
| 2022-04-25 |
+-------------+
current_timestamp：当前的日期加时间
select current_timestamp;
+-------------------------+
| _c0 |
+-------------------------+
| 2022-04-25 15:32:29.09 |
+-------------------------+
to_date：抽取日期部分
select to_date('2022-04-25 15:32:29.09');
+-------------+
| _c0 |
+-------------+
| 2022-04-25 |
+-------------+
year：获取年
select year('2022-04-25 15:32:29.09');
+-------+
| _c0 |
+-------+
| 2022 |
+-------+
month：获取月
select month('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 4 |
+------+
day：获取日
select day('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 25 |
+------+
hour：获取时
select hour('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 15 |
+------+
minute：获取分
select minute('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 32 |
+------+
second：获取秒
select second('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 29 |
+------+
weekofyear：当前时间是一年中的第几周
select weekofyear('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 17 |
+------+
dayofmonth：当前时间是一个月中的第几天
select dayofmonth('2022-04-25 15:32:29.09');
+------+
| _c0 |
+------+
| 25 |
+------+
months_between： 两个日期间的月份
select months_between('2022-01-25','2022-04-25');
+-------+
| _c0 |
+-------+
| -3.0 |
+-------+
add_months：日期加减月
select add_months('2022-01-25',+3);
+-------------+
| _c0 |
+-------------+
| 2022-04-25 |
+-------------+
select add_months('2022-01-25',-3);
+-------------+
| _c0 |
+-------------+
| 2021-10-25 |
+-------------+
datediff：两个日期相差的天数
select datediff('2022-01-25','2022-04-25');
+------+
| _c0 |
+------+
| -90 |
+------+
date_add：日期加天数
select date_add('2022-04-25',-3);
+-------------+
| _c0 |
+-------------+
| 2022-04-22 |
+-------------+
date_sub：日期减天数
减负等于加正
select date_sub('2022-04-25',-3);
+-------------+
| _c0 |
+-------------+
| 2022-04-28 |
+-------------+
last_day：日期的当月的最后一天
select last_day('2022-04-25');
+-------------+
| _c0 |
+-------------+
| 2022-04-30 |
+-------------+
date_format(): 格式化日期
select date_format('2022-04-25 15:20:17','yyyy/MM/dd HH:mm:ss');
+----------------------+
| _c0 |
+----------------------+
| 2022/04/25 15:20:17 |
+----------------------+
常用取整函数
round： 四舍五入
select round(3.14);
+------+
| _c0 |
+------+
| 3 |
+------+
select round(3.54);
+------+
| _c0 |
+------+
| 4 |
+------+
ceil： 向上取整
select ceil(3.14);
+------+
| _c0 |
+------+
| 4 |
+------+
select ceil(3.54);
+------+
| _c0 |
+------+
| 4 |
+------+
floor： 向下取整
select floor(3.14);
+------+
| _c0 |
+------+
| 3 |
+------+
select floor(4.14);
+------+
| _c0 |
+------+
| 4 |
+------+
常用字符串操作函数
upper： 转大写
select upper('Hive');
+-------+
| _c0 |
+-------+
| HIVE |
+-------+
lower： 转小写
select lower('Hive');
+-------+
| _c0 |
+-------+
| hive |
+-------+
length： 长度
select length('Hive');
+------+
| _c0 |
+------+
| 4 |
+------+
trim： 前后去空格
select trim(' Hive ');
+-------+
| _c0 |
+-------+
| Hive |
+-------+
lpad： 向左补齐，到指定长度
select lpad('Hive',1,'l');
+------+
| _c0 |
+------+
| H |
+------+
rpad： 向右补齐，到指定长度
select rpad('Hive',5,'l');
+--------+
| _c0 |
+--------+
| Hivel |
+--------+
regexp_replace：使用正则表达式匹配目标字符串，匹配成功后替换！
select regexp_replace('2020/04/25', '/', '-');
+-------------+
| _c0 |
+-------------+
| 2020-04-25 |
+-------------+
集合操作函数
size： 集合中元素的个数
“map” or “list” is expected at function SIZE
（函数 SIZE 需要“map”或“list”）
select name,deductions from employees;
+-------------------+----------------------------------------------------+
| name | deductions |
+-------------------+----------------------------------------------------+
| John Doe | "Federal Taxes":0.2,"State Taxes":0.05,"Insurance":0.1 |
| Mary Smith | "Federal Taxes":0.2,"State Taxes":0.05,"Insurance":0.1 |
| Todd Jones | "Federal Taxes":0.15,"State Taxes":0.03,"Insurance":0.1 |
| Bill King | "Federal Taxes":0.15,"State Taxes":0.03,"Insurance":0.1 |
| Boss Man | "Federal Taxes":0.3,"State Taxes":0.07,"Insurance":0.05 |
| Fred Finance | "Federal Taxes":0.3,"State Taxes":0.07,"Insurance":0.05 |
| Stacy Accountant | "Federal Taxes":0.15,"State Taxes":0.03,"Insurance":0.1 |
+-------------------+----------------------------------------------------+
select size(deductions) from employees;
+------+
| _c0 |
+------+
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
| 3 |
+------+
map_keys： 返回map中的key
select map_keys(deductions) from employees;
+----------------------------------------------+
| _c0 |
+----------------------------------------------+
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
| ["Federal Taxes","State Taxes","Insurance"] |
+----------------------------------------------+
map_values: 返回map中的value
select map_values(deductions) from employees;
+------------------+
| _c0 |
+------------------+
| [0.2,0.05,0.1] |
| [0.2,0.05,0.1] |
| [0.15,0.03,0.1] |
| [0.15,0.03,0.1] |
| [0.3,0.07,0.05] |
| [0.3,0.07,0.05] |
| [0.15,0.03,0.1] |
+------------------+
array_contains: 判断array中是否包含某个元素
select name,subordinates from employees;
+-------------------+------------------------------+
| name | subordinates |
+-------------------+------------------------------+
| John Doe | ["Mary Smith","Todd Jones"] |
| Mary Smith | ["Bill King"] |
| Todd Jones | [] |
| Bill King | [] |
| Boss Man | ["John Doe","Fred Finance"] |
| Fred Finance | ["Stacy Accountant"] |
| Stacy Accountant | [] |
+-------------------+------------------------------+
select name,array_contains(subordinates,'Bill King') from employees;
+-------------------+--------+
| name | _c1 |
+-------------------+--------+
| John Doe | false |
| Mary Smith | true |
| Todd Jones | false |
| Bill King | false |
| Boss Man | false |
| Fred Finance | false |
| Stacy Accountant | false |
+-------------------+--------+
sort_array： 将array中的元素排序
select name,sort_array(subordinates) from employees;
+-------------------+------------------------------+
| name | _c1 |
+-------------------+------------------------------+
| John Doe | ["Mary Smith","Todd Jones"] |
| Mary Smith | ["Bill King"] |
| Todd Jones | [] |
| Bill King | [] |
| Boss Man | ["Fred Finance","John Doe"] |
| Fred Finance | ["Stacy Accountant"] |
| Stacy Accountant | [] |
+-------------------+------------------------------+
多维分析
grouping sets:多维分析
这个建议看其他大佬的文章
以上是关于Hive常用函数（日期函数，取整函数，字符串操作函数，集合操作函数）的主要内容，如果未能解决你的问题，请参考以下文章