Methods

for

Processing

Disk

Files

 

 

 

If,

in

the

same

job or activation group, two logical files use the

and

 

one

file

is

processed consecutively and one is processed for r

record

can be updated

that

has

already been

placed

in

the

buffe

to

the

program.

In this case, when the record

is

processed

from

file, the

record does

not reflect

the

updated

data.

To

prevent t

CL

command

OVRDBF

and

specify

the

option

SEQONLY(*NO),

which

indicates

that

you

do

not

want

multiple

records transferred

for a consecutivel

For more information on sequential only processing,DB2 UDBsee forthe AS/400

Database Programming.

Sequential-by-Key Processing

For

the sequential-by-key method of processing, records are read fr

key

sequence.

The sequential-by-key method of processing is valid for keyed files primary, secondary, or full procedural files.

For

output files

and for

input files

that

do not

use

random

functions

SETLL,

SETGT,

CHAIN,

or

ADD) and

that

have only

one

record

format,

the

I

RPG compiler defaults to or operates

as

 

though

SEQONLY(*YES)

had

been

fied on the CL command OVRDBF. (The

ILE

RPG

compiler does

not

operat

though SEQONLY(*YES) had been specified

for

update

files.)

SEQONLY(*YES)

allows multiple records to be placed

in

internal

data

management

buffe

records

are then

passed

to

the

ILE

RPG

compiler

one

at

a

time

on

If, in the same job, two files use the same physical file, and o

sequentially and one is processed

for

random

update,

a

record

could

that has already been placed in

the buffer that is presented to

case, when the record is processed from the sequential file,

the

reflect the updated data. To

prevent

this

problem,

use

the CL

comma

and specify the option SEQONLY(*NO),

which indicates that you do

not w

tiple records transferred for

a

sequentially

processed

file.

 

For more information on sequential only processing,DB2 UDBsee forthe AS/400

Database Programming manual.

Examples of Sequential-by-Key Processing

The following three examples show you different ways of using the sequential-by-key method of processing data.

DATA DESCRIPTION SPECIFICATIONS (DDS):Figure 144 on page 294 and

Figure 145 on page 294 shows the data description specifications (DDS

physical files used by the examples.

Figure 146 on page 294 shows t

the logical file used by the first

three examples.

Chapter 16. Accessing Database 293Files

Page 316 Page 318
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Image 317
IBM AS/400 Examples of Sequential-by-Key Processing, Database Programming manual
Page 316 Page 318

AS/400 specifications

The IBM AS/400, now known as the IBM iSeries, is a midrange computer system that has been a cornerstone of enterprise computing since its introduction in 1988. Designed to provide a robust platform for business applications, the AS/400 is celebrated for its reliability, scalability, and integrated database capabilities.

One of the key features of the AS/400 is its Integrated Operating Environment, which blends hardware and software resources seamlessly. This integration allows businesses to execute diverse workloads, ranging from traditional applications to modern web-based services, all on a single platform. The operating system, OS/400 (now IBM i), offers a rich set of APIs and tools for developers, simplifying application development and management.

Another standout characteristic of the AS/400 is its built-in database, DB2 for i. This powerful relational database management system allows for efficient data handling and provides advanced features such as support for SQL, XML, and JSON, making it easier for businesses to manage their data and integrate it with other systems. The database's tight integration with the operating system enables high performance and security.

In terms of scalability, the AS/400 can accommodate small businesses as well as large enterprises, with the ability to support hundreds of users simultaneously. Its architecture allows for easy upgrades in hardware, meaning that organizations can scale their systems without replacing the entire infrastructure.

Security is another critical attribute of the AS/400. With a sophisticated security model, it offers built-in user authentication, access control, encryption, and auditing capabilities to protect data and applications from unauthorized access.

The AS/400 also supports multiple programming languages, including RPG, COBOL, Java, and PHP, giving organizations the flexibility to choose the development tools that best fit their needs. This diversity helps maintain legacy applications while also developing new ones that leverage modern technologies.

Moreover, the platform supports both traditional green-screen interfaces and modern graphical user interfaces, allowing organizations to transition smoothly into contemporary user experience paradigms.

Overall, the IBM AS/400 stands out as a resilient, flexible, and secure computing platform that enables organizations to effectively manage their business operations, streamline processes, and adapt to changing market demands. Its unique combination of integrated features and capabilities ensures that it remains relevant in today's fast-paced technology landscape.
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