HiveSQL中date_sub的用法

 

語法：

VARCHAR DATE_SUB(VARCHAR startdate, INT days)
VARCHAR DATE_SUB(TIMESTAMP time, INT days)　

參數：

參數	數據類型
startdate	VARCHAR
time	TIMESTAMP
days	INT

 

 

 

 

 

 

 

定義：返回startdate減去days天數的日期。返回VARCHAR類型的yyyy-MM-dd日期格式。若有參數為null或解析錯誤，返回null。

測試案例：

SELECT DATE_SUB(date1, 30) as var1,
 DATE_SUB(TIMESTAMP '2017-10-15 23:00:00',30) as var2,
 DATE_SUB(nullstr,30) as var3
FROM T1

　　

測試結果：

var1(VARCHAR)	var2(VARCHAR)	var3(VARCHAR)
2017-09-15	2017-09-15	null

 

 

場景案例：

-- 編寫連續7天登錄的總人數

 

t1表
Uid dt login_status(1登錄成功,0異常)
1 2019-07-11 1
1 2019-07-12 1
1 2019-07-13 1
1 2019-07-14 1
1 2019-07-15 1
1 2019-07-16 1
1 2019-07-17 1
1 2019-07-18 1
2 2019-07-11 1
2 2019-07-12 1
2 2019-07-13 0
2 2019-07-14 1
2 2019-07-15 1
2 2019-07-16 0
2 2019-07-17 1
2 2019-07-18 0
3 2019-07-11 1
3 2019-07-12 1
3 2019-07-13 1
3 2019-07-14 1
3 2019-07-15 1
3 2019-07-16 1
3 2019-07-17 1
3 2019-07-18 1

-- 建表
create table if not exists c_t1(
uid int,
dt string,
login_status int
)
row format delimited fields terminated by ' '
;


-- 導入數據
load data local inpath '/opt/datas/t1.txt' into table c_t1;

-- 思路一
select
uid,
dt，
row_number() over(distribute by uid sort by dt) rm
from c_t1
where login_status = 1
;  t1 

-- 思路二
select 
t.uid,
date_sub(t1.dt,dt.rm) dt
from
(
select
uid,
dt
row_number() over(distribute by uid sort by dt) rm
from c_t1
where login_status = 1
)t1
; t2

-- 思路三
select
uid,
dt
from
(
select 
t1.uid,
date_sub(t1.dt,t1.rm) dt
from
(
select
uid,
dt,
row_number() over(distribute by uid sort by dt) rm
from c_t1
where login_status = 1
)t1
)t2
group by 
uid,
dt
having 
count(uid) > 7
;