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Monday, May 9, 2016

What is the precise definition of JDE's Julian Date format?

What is the precise definition of JDE's Julian Date format?


I am writing code to convert from a Gregorian date to a JDE (J.D.Edwards) Julian date.

Note: a JDE Julian date is different from the normal usage of the term Julian date.

As far as I can work out from Googling, the definition of a JDE Julian date is:

1000*(year-1900) + dayofyear  

where year is the 4-digit year (e.g. 2009), and dayofyear is 1 for 1st January, and counts up all year to either 365 or 366 for 31st December (depending whether this is a leap year).

My question is this: are years before 1900 supported? If so, does the above formula still hold, or should it be this:

1000*(year-1900) - dayofyear  

(note minus instead of plus.)

or something else?

Does anyone have a link to the official documentation for this date format?

Answer by VonC for What is the precise definition of JDE's Julian Date format?


The "JDE Julian Date Converter" does return a negative value for:

1809/07/23 : -90635  

As opposed to the classical Julian Date:

The Julian date for CE  1809 July 23 00:00:00.0 UT is  JD 2381986.50000  

Here is a example of JD EDWARDS (AS/400 software) Julian Date, but that is not an "official" documentation and it does not seems to support dates before 1900...

Note: this "ACC: How to Convert Julian Days to Dates in Access and Back" does not support date before 1900 either... as it speaks about an "informal" Julian day, commonly used by government agencies and contractors.

The informal Julian day format used in this article is the ordinal day of a year (for example, Julian day 032 represents February 1st, or the 32nd day of the year).
Variations on informal Julian day formats include using a preceding two-digit year (for example 96032 for 2/1/96) and separating the year with a dash (for example 96-032).
Another, less popular, Julian day format uses a one digit year (for example 6-032). These additional formats do not uniquely identify the century or decade. You should carefully consider the consequences when using these formats; for example, the Julian day 00061 can be interpreted as 3/1/2000 or 3/2/1900.

Answer by Peter Mortensen for What is the precise definition of JDE's Julian Date format?


Update: Sorry, JDE is probably something else. But for reference:

The JDE I know is different. From page 59 in the book "Astronomical algorithms" (Jean Meeus, ISBN 0-943396-35-2):

"If the JD corresponds to an instant measured in the scale of Dynamical Time (or Ephemeris Time), the expression Julian Ephemeris Day (JDE) is generally used. (Not JED as
it is sometimes written. The 'E' is a sort of index appended to 'JD')"

JD and JDE (for the same point in time) are close in value as the difference UT and ET is on the order of minutes. E.g. ET-UT was 56.86 seconds in 1990 and -2.72 seconds in 1900.

There is also MJD (Modified Julian Day):

MJD = JD - 2400000.5

Zero point for MJD is 1858-11-17, 0h UT.


Note that JD as Julian date is a misnomer. It is Julian day. The JD has nothing to do with the Julian calendar. (This is in disagreement with the Wikipedia article, this is from the author of the book mentioned above, Jean Meeus - a Belgian astronomer specializing in celestial mechanics.)

Answer by YoNGaR for What is the precise definition of JDE's Julian Date format?


Maybe off from the question, you can convert in Excel using the following formula:

Convert Julian to Date in Excel

In Cell A2 place a Julian date, like 102324
in Cell B2 place this formula: (copy it in)
=DATE(YEAR("01/01/"&TEXT(1900+INT(A2/1000),0)),MONTH("01/01/"&TEXT(1900+INT(A2/1000),0)),DAY("01/01/"&TEXT(1900+INT(A2/1000),0)))+MOD(A2,1000)-1

The date 11/20/02 date will appear in cell B2

Convert Date to Julian in Excel

In Cell C2 copy this formula:
=(YEAR(B2)-2000+100)*1000+B2-DATE(YEAR(B2),"01","01")+1

This will convert B2 back to 102324

Answer by bazscott for What is the precise definition of JDE's Julian Date format?


The JDE Julian date consists of CYYDDD which is Century, Year, Day of year.

Century is zero for 20th e.g. 19XX and one for 21st e.g. 20XX.

The year is two digits. So 101001 is 1 January 2001

As you can see this will not support dates before 1900.

See this Oracle page for a simple and official explanation: About the Julian Date Format

Answer by Qpgmr for What is the precise definition of JDE's Julian Date format?


Save the below source code in a source member called JDEDATES. Use the runsqlstm on the first line to create the functions. You can then do things like

select  jde2date(A1UPMJ), f.* from f00095 f                              

and see a real date.

Source:

--RUNSQLSTM SRCFILE(qtxtsrc) SRCMBR(JDEDATES) COMMIT(*NONE)  NAMING(*SQL)    -- jde 2 date                                                                         create function QGPL/jde2date ( d decimal(7,0))                                     returns date                                                                        language sql                                                                        deterministic                                                                       contains sql                                                                           SET OPTION DATFMT=*ISO                                                           BEGIN                                                                                if d=0 then return null;                                                            else                                                                                     return date(digits(decimal(d+1900000,7,0)));                                   end if;                                                                            end;                                                                            -- date 2 jde                                        create function QGPL/date2jde ( d date)              returns decimal(7,0)                                 language sql                                         deterministic                                        contains sql                                            SET OPTION DATFMT=*ISO                            BEGIN                                                 if d is null then return 0;                          else                                                 return (YEAR(D)-1900)*1000+DAYOFYEAR(D);             end if;                                             end ;                                                

Answer by Adge Cutler for What is the precise definition of JDE's Julian Date format?


A sample of VBA code to convert back and forth between JDE Julian Date and Gregorian:

Public Const Epoch = 1900  Public Const JDateMultiplier = 1000  Public Const FirstJan = "01/01/"    Public Function Julian2Date(ByVal vDate As Long) As Date        Dim Year As Long      Dim Days As Long      Dim SeedDate As Date        '   Day Number      Days = vDate - (Int(vDate / JDateMultiplier) * JDateMultiplier) - 1      '   Calendar Year      Year = ((vDate - Days) / JDateMultiplier) + Epoch      '   First Day of Calendar Year      SeedDate = CDate(FirstJan + CStr(Year))        '   Add Number of Days to First Day in Calendar Year      Julian2Date = DateAdd("d", Days, SeedDate)    End Function    Public Function Date2Julian(ByVal vDate As Date) As Long        Dim JYear As String      Dim BeginDate As Date      Dim JDays As Long        '   Calendar Year      JYear = Format(Year(vDate), "0000")      '   First Day of Calendar Year      BeginDate = CDate(FirstJan + JYear)      '   Day Number      JDays = DateDiff("d", BeginDate, vDate) + 1        '   Add Number of Days to Year Number      Date2Julian = ((CLng(JYear) - Epoch) * JDateMultiplier) + JDays    End Function  

I have tried to make it as clear and simple as possible, and to this end I have intentionally left out any error trapping. However, you should be able to add the code to a VBA module and call them directly from your own code.

I also include some useful snippets of T-SQL:

Todays Date as JDE Julian Date:

 (datepart(yy,getdate())-1900) * 1000 + datepart(dy, getdate())  

Convert JDE Julian Date to Gregorian (DD/MM/YYYY), replace XXXXXX with the column name containing the JDE Julian Date:

convert (varchar, dateadd (day,convert (int, right(XXXXXX,3)) - 1, convert (datetime, ('1/1/' + convert ( varchar, (cast(left(right(XXXXXX+1000000,6),3) as varchar) + 1900))))),103)  

If you require a different Gregorian format, replace the 103 value (right at the end) with the applicable value found here: https://msdn.microsoft.com/en-us/library/ms187928.aspx

Answer by Douglas G. Allen for What is the precise definition of JDE's Julian Date format?


I have an easy way for C using time now and epoch 1970, 01, 01 midnight if anybody is interested. But this is for Julian Day Numbers which is not the same as JDE but they are similar in respect to using math to compute days and I'm sure this idea could be adapted for JDE. Sometimes people just confuse the two like I do. Sorry. But still this is an example of using a time reference which should always be done and since most computers use this it would be just as easy for us not to get too bogged down in dates and just use days before or after this epoch.

Since JDE is now owned by Oracle, they also now support Julian_Day. see: https://docs.oracle.com/javase/8/docs/api/java/time/temporal/JulianFields.html

#include   #include   #define EPOCH (double)  2440587.5 /* Julian Day number for Jan. 01, 1970 midnight */  int main ()  {   double days = time(0)/86400.0;     printf ("%f days since January 1, 1970\n", days);     printf ("%f\n", days + EPOCH);     return 0;    }  

Answer by Bond for What is the precise definition of JDE's Julian Date format?


Wow, there's a lot of complicated code in some of these answers just to convert to and from JDE julian dates. There are simple ways in Excel and VBA to get there.

FROM JULIAN

Excel (assuming julian date is in A1):

=DATE(1900+LEFT(A1,LEN(A1)-3),1,RIGHT(A1,3))  

VBA (from julian date, j, stored as String):

d = DateSerial(1900 + Left$(j, Len(j) - 3), 1, Right$(j, 3))  

VBA (from julian date, j, stored as Long):

d = DateSerial(1900 + Left$(j, Len(CStr(j)) - 3), 1, Right$(j, 3))  

TO JULIAN

Excel (assuming date is in A1):

=(YEAR(A1)-1900)*1000+A1-DATE(YEAR(A1),1,0)  

VBA (to a Long, j):

j = (Year(d) - 1900) * 1000 + DatePart("y", d)  


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