Convert datetime string from specific time zone to another specific timezone - hive

Question

I have a HIVE table of orders from different locations. This table contains a string column containing the date and time of each order. There is also another column with the corresponding timezone.For some reason, however, the value in the timezone column is not the local one. Then for each date, I have the corresponding timezone and a target timezone to convert. Like this:
with orders as (
select 1 as order_id, '2022-07-20 15:04:12' as create_time, 'UTC' as create_tz, 'BRT' as target_tz
union all
select 2 as order_id, '2022-07-20 17:34:14' as create_time, 'CET' as create_tz, 'PST' as target_tz
) select * from orders;
order_id
create_time
create_tz
target_tz
1
2022-07-20 15:04:12
UTC
BRT
2
2022-07-20 17:34:14
CET
PST
I need to print a string column with the local date and time (and also make the timezone explicit). Like this:
order_id
local_time
1
2022-07-20 12:04:12 BRT
2
2022-07-20 08:34:14 PST
My approach was to convert everything to UTC and then print it using the function from_unixtime, however it seems that this function always print the result in the client's time (in my case CST). I didn't find a way to set a target timezone for each record.
with orders as (
select 1 as order_id, '2022-07-20 15:04:12' as create_time, 'UTC' as create_tz, 'BRT' as target_tz
union all
select 2 as order_id, '2022-07-20 17:34:14' as create_time, 'CET' as create_tz, 'PST' as target_tz
) select
order_id,
from_unixtime(unix_timestamp(concat(create_time, ' ', create_tz), 'yyyy-MM-dd HH:mm:ss z'), 'yyyy-MM-dd HH:mm:ss z')
from orders;

Answer 1

It is not an elegant workaround, but it seems to work:
with orders as (
select 1 as order_id, '2022-07-20 15:04:12' as create_time, 'UTC' as create_tz, 'BRT' as target_tz
union all
select 2 as order_id, '2022-07-20 17:34:14' as create_time, 'CET' as create_tz, 'PST' as target_tz
) select
order_id,
concat(from_unixtime(
unix_timestamp(create_time)
+ unix_timestamp(concat('1970-01-01 00:00:00', ' ', create_tz), 'yyyy-MM-dd HH:mm:ss z')
- unix_timestamp(concat('1970-01-01 00:00:00', ' ', target_tz), 'yyyy-MM-dd HH:mm:ss z')
), ' ', target_tz)
from orders;