What is the benefit of using Externally Described files
over Internally
Described?
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Answer / nani
Externally Described files:
---------------------------
File definitions and descriptions defined outside of the programs only.
Internally Described files:
---------------------
this files are also called as program described files.
File definitions and descriptions defined inside of the program only.
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Answer / ankush chaudhary
Defining data files as externally described has several
advantages over program desribed files:
1. If you design the file using database design principles,
externally defined files can reduce the need for
duplication of data across fiels. This kind of duplication
is called redundancy. Because all programs using a given
file use the same field definition and names. Externally
described files impose standardisation among programs and
across applications.
2. Externally described also also increase programmers
efficiency and reduces errors because programmers don't
need to duplicate the file definition effort each time they
need to reference a file within the a program.
3. If it is necessary to add a field to a fiels records or
to change a fields definition, these changes need to made
in only one place (in the externally described file) rather
than in every program that uses that file. THus simplifying
maintenance.
Hope this much difference is suffient :))
| Is This Answer Correct ? | 1 Yes | 2 No |
Answer / kumar vikas
You can check with dspfd(PF) which will show that file is described externally
and dspfd(flatf) which will show that file is not described externally.
| Is This Answer Correct ? | 0 Yes | 1 No |
Answer / rami
The input buffer for this file is created at the time of
compilation itself whereas in case of program description
the input buffer will be created at the time of running the
program.
| Is This Answer Correct ? | 1 Yes | 3 No |
Answer / newbiezhang
no idea, what is the Externally Descibed files?
maybe the Data Describe File? include PF source file and LF
source file?
it's a better idea to store data format in a externally
file other than store it in the program. because we can
change data format more easier.
| Is This Answer Correct ? | 0 Yes | 3 No |
Answer / prima krishnan
Program Described:-
For program-described files, the file name entered in
positions 7 through 14 must also be entered on:
° Input specifications if the file is a primary, secondary,
or full procedural file
° Output specifications or an output calculation operation
line if the file is an output, update, or combined file, or
if the file is an input file and records are also being
added to the file
° Extension specifications if the file is a table, array, or
record address file, or a file processed by a record-address
file
° Calculation specifications if the file name is required
for the operation code specified
° Line counter specifications if the device is a printer and
default values are to be overridden.
Externally Described File
For externally described files, the file name entered in
positions 7 through 14 is the name used to locate the record
descriptions for the file. The following rules apply to
externally described files:
° Input and output specifications for externally described
files are optional. They are required only if you are adding
RPG/400 functions, such as control fields or record
identifying indicators, to the external description retrieved.
° When an external description is retrieved, the record
definition can be referred to by its record format name on
the input, output, or calculation specifications.
° A record format name must be a unique symbolic name.
° A logical file with two record formats of the same name
cannot have the duplicate format names renamed and cannot be
externally described. However, such a file can be accessed
if it is program described.
| Is This Answer Correct ? | 0 Yes | 4 No |
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