Re: Difference

["William A.\(Tony\) Corbett" <corbett@xxxxxxxxxxxxxxx>]

ReadC will read the next changed subfile record in the subfile (as indicated
by Modified Data Tags).  I don't usually like to use this opcode, since ANY
other I/O operation to the subfile will screw up the MDT's and ReadC won't
work "as expected".  Most changes (IMO) shouldn't be done on the subfile
anyway, since you normally need an exclusive lock on the record you're
changing.

IE., if you change some records (which you expect ReadC to pick up), then
hit a cmdkey on the screen, all bets are off on the MDT's staying put.

Most of the subfile programs I write have stuff like: F1-Help, F4-Prompt,
F5-Edit, etc.  I/O to the subfile will often screw up the MDT's and the next
ReadC will not pick up all the records you'd have expected it to.  And then
there's maintenance, often by another programmer, who may change something
which makes your old ReadC logic not work anymore.

This is just based on my experiences and may/may not be accurate in your
situation.

You wrote:
Dear Guys,=0D
         What's the difference between CHAIN and READC for controlling subf=
ile record? As I usually use ReadC to read the next change subfile record n=
umber, But I found some guys use 'Chain' to read the subfile record. any re=
ponsonse?

AS/Resources, Inc.
William A.(Tony) Corbett
IBM Certified Specialist - AS/400 Developer
http://www.asresources.com
corbett@asresources.com
770-587-4812 (no answer forwards to mobile)
fax:  404-663-4737