进度 SQL：将儒略日期转换为日期时间

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