• Subject: Re: RPG - conversion vs re-write
  • From: John Carr <74711.77@xxxxxxxxxxxxxx>
  • Date: Wed, 10 Sep 1997 18:42:52 -0400

RE:     Re: RPG - conversion vs re-write


>And John, you still haven't said what inaccurate date we should use to
>signify a date field that is unfilled yet.  

Do the dates the same way you're doing them now.   00/00/00 means something
unique in your code, right?   Like  ( XXXDATE  IFEQ  0 ) or something like
that.   Have a "Default" date in your D-Spec initialized to 0001-01-01 and 
heck call it ZERO_DATE if you want to.  Then change the code to say
(XXXDATE IFEQ   ZERO_DATE)  It means the same to your logic.  

Unless you use the CHANGE keyword in DDS (which still might have problems)
in your code right now you don't know if the user keyed in a zero date 
on the display file entry field or she/he just left it blank(Zero - means
a real null response?).  

The real problem is,  what does zero (00/00/00) mean to your applications?
Is it an un-initialized field?  How does it get into the data base file 
to begin with?  Display file entry screen?  If that is the case just 
transmutate it from screen to data base file.   If the user enters a 
00/00/00 convert that to a 0001-01-01 in your data base file. 

It will be just as easy to sort, select/omit, extract, etc.

Check where you really use the 00/00/00 and see what your REALLY trying
to mean/denote in that instance.  

Sometimes when we first write out a record we may not know all the 
information.  In alot of Customer Order files if you don't know the 
expected ship date, or actual ship date, or expected completion date, 
or actual completion date, or , or , or.  What do you put in those fields
now and why?   Zero's aren't really correct are they?  Neither are
99/99/99 what does that suppose to mean?   Maybe Nulls for the 
"Actual" dates but for the "Expected" dates? 

Come to an agreement with your users the same way you did when the 
system started and say; 

"Hey everybody, when you see a 00/00/00 in actual ship date, it means we
 don't know. Now you will see a 0001-01-01, it means we still don't know.

A rose is a rose. 

Find the meaning of the "Figurative Constant" 00/00/00 or 99/99/99
and make a new representation for that meaning to your users. 
(Like 0001-01-01 or 9999-12-31)

John Carr  CDP 
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