如何从当前日期减去一天，然后在Hive中转换为字符串

Question

Here is the case. I'm trying to make select syntax to get data from last day (today we have 21.10 so as a result I should have data with 20.10 date query will be a part of ETL proces in Talend so I can't simply do where date = '2016-10-20' ) The problem is that all columns in data source are in VARCHAR or STRING type - date also. Source is on Hive Hadoop.

My code:

select 
cast(to_date(from_unixtime(unix_timestamp(dzien ,'yyyyMMdd'), 'yyyy-MM-dd')) as date),
count(ns_utc) as ILOSC_ODSLON
from portal.portal_data 
where
portal_data.opl_ev_ty is null 
and portal_data.opl_ev_as is null
and cast(to_date(from_unixtime(unix_timestamp(dzien ,'yyyyMMdd'), 'yyyy-MM-dd')) as date) = CAST(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP()))as date) - interval '1' day

GROUP BY 
cast(to_date(from_unixtime(unix_timestamp(dzien ,'yyyyMMdd'), 'yyyy-MM-dd')) as date)

With that code query returns nothing exept columns name. The problem is probably with this part = CAST(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP()))as date) - interval '1' day .

I made some tests. When I'm running this query

select CAST(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP()))as date) - interval '1' day

result is 2016-10-20 00:00:00.0 and part 00:00:00.0 probably ruins my query, becasue when in main query instead of = CAST(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP()))as date) - interval '1' day I'm putting condition = '2016-10-20' result is as expected.

Can you please guide me how to solve this problem?

Instead of Hue I'm using SQL Workbench

Answer 1

once you parsed the date then use date_sub function that is available in hive

date_sub(string startdate, int days) 

date_sub('2008-12-31', 1) = '2008-12-30'

You can even follow the link below.

https://www.qubole.com/resources/cheatsheet/hive-function-cheat-sheet/

Answer 2

DATE_SUB is Available in HIVE 2.1.0

date_sub(date/timestamp/string startdate, tinyint/smallint/int days)

Subtracts a number of days to startdate: date_sub('2008-12-31', 1) = '2008-12-30'.

Prior to Hive 2.1.0 (HIVE-13248) the return type was a String because no Date type existed when the method was created.

Answer 3

问题是你试图从date减去一天的方式。我建议从where子句中的unix时间戳减去一天中的秒数（86400） -

CAST(TO_DATE(FROM_UNIXTIME(UNIX_TIMESTAMP()-86400))as date) 

Answer 4

For versions >= Hive 2.0 Try this:

select current_date;

Then try this:

select date_sub(current_date, 1);

It should give you current date minus 1 day.

Answer 5

cast（date_sub（CURRENT_DATE，1）as string）