#常规建表语句
create table tv_corpus
(device_id  string,
eposide_id  string,
channel_id  string)
partitioned by(
dt string,
scene string);

#显示字段名 
set hive.cli.print.header=true;
set hive.resultset.use.unique.column.names=false;

#查看表的建立语句
show create table tv_corpus;

#建立一张临时表存储查询结果
create temporary table  tv_corpus select ... from 

#将存储查询结果插入某表
insert overwirte(into) table tv_corpus partition (dt='${bizdate}')
select ... from 

#with..as子查询
with t1 as (select .. from tv_corpus),
t2 as (slect .. from falls_corpus)
select t1.*, t2.* from t1,t2 where...

# not in的表达（hive sql不支持not in）
select a.* from 
(select * from t1)a
left join 
(select * from t2)b
on a.uid = b.uid where b.uid is null;

#concat cnocat_ws...
concat(a,b,c)  #连接abc字段
concat_ws('-',a,b)  #以-分隔符连接字段
group_concat(a).. group by b #返回以b聚合后的a值

#split 
select split(device_id,'#')[0] as device_id from tv_corpus;

#explode 将分割后的字符打散成多行
select explode(split(device_id,'#')) as device_id from tv_corpus;

#lateral view
select myTable.r_source, cnt(1) from
(select r_source  from tv_corpus where dt = '${bizdate}' 
lateral view explode(split(r_source,'@')) myTable as r_source  
group by myTable.r_source

#get_json_object ：json的解析函数
对于[{"name":"王二狗","sex":"男","age":"25"},{"name":"李狗嗨","sex":"男","age":"47"}]
#取出第一个json对象
SELECT get_json_object(json,"$.[0]") FROM person;
#返回
{"name":"王二狗","sex":"男","age":"25"}

#列转行
collect_set : 去重
collect_list: 不去重

Coalesce   取指定内容（列）中第一个不为空的值 可以理解为 ifnull() 是其简化版
https://www.cnblogs.com/yanglang/p/10081181.html

union 并集  
intersect 交集 
except 差集   https://www.cnblogs.com/kissdodog/archive/2013/06/24/3152743.html

regexp_replace   正则替换  https://blog.csdn.net/qq_20989105/article/details/77894949

array_contains  ARRAY_CONTAINS(pages_sns, "a") AS .. 判断是否包含‘a’   
!array_contains是不包含的

substr   substr(string,1,3) 得到str 从左往右取3字长  从右往左取的话 substr(string,-1,3) 得到ing
 
round()函数遵循四舍五入原则，用于把数值字段舍入为指定的小数位数
floor(value)函数返回小于或等于指定值（value）的最小整数
ceiling(value)函数返回大于或等于指定值（value）的最小整数

trim(device_id)  移除字符首尾空格。 还有 ltrim rtrim https://www.1keydata.com/cn/sql/sql-trim.php