DDS for display files
Use this record-level keyword to specify that, when your program sends an
input operation to this record format, the OS/400 program is to return the
same data that was returned on the previous input operation sent to this
record format. The RTNDTA keyword is ignored if the record format has
not already been read. When the RTNDTA keyword is in effect, your
program can reread data on the display without requiring the OS/400 program to
actually pass data from the display device to your program.
This keyword has no parameters.
The RTNDTA keyword is ignored in the following situations:
- On the input portion of an output/input operation (Put-Get operation)
- On an input operation that is preceded by an output operation to the same
record format
The RTNDTA keyword has effect only on an input operation sent to the same
record format without an intervening output operation to that record
format.
You can use RTNDTA as follows:
- Use RTNDTA to allow a main program to read a record format that is changed
by a workstation user. The data read tells the main program which
subprogram to call. The subprogram sends an input operation to the same
record format, with RTNDTA in effect, to read the same data. This
procedure can substitute for passing parameters to subprograms.
- Note:
- SHARE(*YES) must be specified for both display files.
- Use RTNDTA to allow an RPG III program to perform file maintenance with
less locking of records in the database. For instance, the program
reads a database record and displays the record at the display device.
The workstation user reviews the record, makes any required changes, and
presses the Enter key. While the workstation user is making changes,
the database record, if locked, is unavailable to other programs. Hence
it is recommended to leave the database record unlocked. However, when
the program reads the record from the display and updates the database record,
the database record overlays the internal representation of the display record
in the program. Instead of preventing the overlay by using different
field names for the display record and the database record, the program
rereads the display file. With RTNDTA specified, the program retrieves
the display record again and can then finish updating the database.
If the UNLOCK keyword is specified, the RTNDTA keyword cannot be
specified.
Option indicators are not valid for this keyword.
Example:
The following example shows how to specify the RTNDTA keyword.
|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A R RECORD1 RTNDTA
00020A FLD1 5 I 2 2
00030A FLD2 5 B 3 2
A
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