Progress SQL : Convert Julian Date into datetime - sql

Question

I working for a client who uses PROGRESS database SQL (i didn't knew this kind of database, so it's my first time that i work on it).
My problem it's all the dates are in Julian-date, and i want to convert them into datetime. But i haven't found any document or help online that deals with this.
The only document i found it's:
https://knowledgebase.progress.com/articles/Article/How-to-Obtain-a-Julian-Date-in-Progress
But i want to do exactly the opposite.
For example in postgresql:
select to_timestamp(column1::text,'J')
from table1
But on PROGRESS it's harder and there is less information and examples than the others databases on the web
Thank you in advance for your help

Answer 1

Character
In case your Julian date is stored in a field with the character data type, you can use instr to pull it apart and then reassemble it into a timestamp:
select
-- my character field containing 92182.3966
descr,
-- get the year
floor( cast( left( descr, instr( descr, '.' ) - 1 ) as integer ) / 1000 ) as 'year',
-- get the day
mod( cast( left( descr, instr( descr, '.' ) - 1 ) as integer ), 1000 ) as 'day',
-- get the time
cast(
'0' + right( descr, length( descr ) - instr( descr, '.' ) + 1 )
as float
) as 'time',
-- combine all to timestamp
cast(
-- get first day of year
cast(
to_char(
floor( cast( left( descr, instr( descr, '.' ) - 1 ) as integer ) / 1000 )
+ 1900 -- !!! beware
)
+ '-01-01'
as date
)
-- add days
+ mod( cast( left( descr, instr( descr, '.' ) - 1 ) as integer ), 1000 )
as timestamp
)
-- add milliseconds
+ cast(
cast(
'0' + right( descr, length( descr ) - instr( descr, '.' ) + 1 )
as float
) * 86400 * 1000
as integer
) as 'timestamp'
from pub.ddcapp
where application = 'JULIAN'
This reports that the time is 1992-07-01 09:31:06.24 which is 1 second later than what your link states it was translated from.
Decimal
If on the other hand your field is a decimal, it is a lot simpler:
select
-- my decimal field containing 92182.3966
open_bal,
-- get the year
floor( open_bal / 1000 ) as 'year',
-- get the day
mod( open_bal, 1000 ) as 'day',
-- get the time
open_bal - floor( open_bal ) as 'time',
-- combine all to timestamp
cast(
cast(
to_char(
floor( open_bal / 1000 )
+ 1900 -- !!!
)
+ '-01-01'
as date
)
+ mod( open_bal, 1000 )
as timestamp
)
+ ( open_bal - floor( open_bal ) ) * 86400 * 1000
as 'timestamp'
from pub.ledbal
where adm_nr = 0