Methods for Processing Disk Files

Random-by-Key Processing

For the random-by-key

method of

processing, a search argument

that

id

key of the record

to be

read is

specified in factor 1 of the

for the CHAIN operation. Figure 151 on

page 300 shows an example of a

externally described

DISK

file

being

processed randomly by

key.

The

record can be read from the file either during detail calculations culations.

The random-by-key method of processing is valid for a full procedural nated as an input file or an update file.

For an externally described file, position 34 of the file descripti contain a K, which indicates that the file is processed according that is built on keys.

The

data description

specifications (DDS)

for the file

specifies

th

the key value (the key

field).

Position

35

of

the

file description

blank.

 

 

 

 

 

 

 

 

 

 

 

A program-described file

must

be

designated

as

an

indexed

file

(I

and

position 34 of

the

file

description

specification

must

contain

a

Z. The length

of

the

key

field is identified in positions 29-33 of

specification,

and

the

starting

location

of the

key field is specif

keyword.

Data description specifications must be

used

to

create th

a program

described input

file

(see

“Indexed

File”

on

page 288).

Example of Random-by-Key Processing

The following is an example of how to use the random-by-key method o essing data. Figure 144 on page 294 and Figure 150 show the data de specifications (DDS) for the physical files used by EMSTUPD ( Figure page 300).

A*****************************************************************

A*

RELATED PGMS:

EMSTUPD

 

 

 

 

*

A*

DESCRIPTIONS:

This

is the

DDS

for the physical

file CHANGE. *

A*

 

It contains

one

record

format called CHGREC.

*

A*

 

This

file contains new

data that

is used to

*

A*

 

update the EMPMST file.

 

 

*

A*****************************************************************

A*

AR CHGREC

A

ENUM

5

0

TEXT('EMPLOYEE NUMBER')

A

NNAME

20

 

TEXT('NEW NAME')

A

NTYPE

1

 

TEXT('NEW TYPE')

A

NDEPT

3

0

TEXT('NEW

DEPARTMENT')

A

NNHRS

3

1

TEXT('NEW

NORMAL WEEK HOURS')

AK ENUM

Figure 150.

DDS for database file CHANGE (physical file)

 

 

EXAMPLE

PROGRAM:

 

 

In this example, the

EMPMST file is

defined

as an

Full-Procedural

file.

The update file CHANGE is to be

processed by ke

for

each

of

the

externally described

files (EMPMST

and CHANGE)

identif

ENUM field as the key field. The read/update processes are all co operations specified in the Calculation Specifications.

Chapter 16. Accessing Database 299Files

Page 322 Page 324
Page 323
Image 323
IBM AS/400 manual Example of Random-by-Key Processing, Emstupd Descriptions, Nnhrs
Page 322 Page 324

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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