Re: Can't RPG Update a NULL Field?

["Michael Naughton" <michael_naughton@xxxxxxxxxxxx>]

This is just a guess, but I know in other systems when a field has a value of "null" it basically means the field doesn't exist. IIRC, the iSeries doesn't store fields in records contiguously, necessarily; instead, it puts them wherever and then uses
pointers to locate them. Might a field with a null value be a field with no pointer (i.e. the iSeries hasn't yet allocated any storage space for it)? In which case, how would you update it -- where would the value go? Initializing the field to a default
value then means that it _has_ been created, and therefore it can be updated.

Just a guess . . .

Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx> writes:
> Riddle me this...I was trying to update a record using the RPG UPDATE
> opcode. I first tried the %Fields parm (which I usually use), and the
> fields weren't being updated. So I took off the %Fields - no change. I
> had specified H AlwNull(*UsrCtl), which I thought would allow me to do
> as I pleased with a null field. It wasn't until is set the fields that
> I was trying to update to their default values (zeros, blanks) that I
> was able to programmatically update the fields that contained a null.
> Is this WAD or am I missing something? Thanks...


Mike Naughton
Senior Programmer/Analyst
Judd Wire, Inc.
124 Turnpike Road
Turners Falls, MA  01376
413-863-4357 x444
mnaughton@xxxxxxxxxxxx
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