Using Program-Described Disk Files

On the file description specifications, the length of the key field positions 29 through 33 (the combined number of positions required for and ITEM fields). The starting position of the key field is described keyword KEYLOC (starting in position 44). The starting position must specif first position of the first key field.

*..

1

...+

... 2

...

+...

3 ...

+

... 4 ...

+...

5 ...

+

6

+

7

...+...

*

 

 

 

FFilename++IPEASFRlen+LKlen+AIDevice+.Keywords+++++++++++++++++++++++++++++

 

FORDDTLL

IP

F

120

10AIDISK

KEYLOC(15)

 

 

 

 

 

 

 

*..

1

...+

... 2

...

+...

3 ...

+

... 4 ...

+...

5 ...

+...

6 ...

+...

7

...+...

*

 

DName+++++++++++ETDsFrom+++To/L+++IDc.Keywords+++++++++++++++++++++++++++++

 

DKEY

 

 

DS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

D K1

 

 

 

 

 

1

 

5

 

 

 

 

 

 

 

 

 

D K2

 

 

 

 

 

6

 

10

 

 

 

 

 

 

 

 

 

*..

1

...+

... 2

...

+...

3 ...

+

... 4 ...

+...

5 ...

+...

6 ...

+...

7

...+...

*

 

CL0N01Factor1+++++++Opcode(E)+Factor2+++++++Result++++++++Len++D+HiLoEq.￿

...

 

C

 

 

 

 

MOVE

 

ORDER

 

K1

 

 

 

 

 

 

 

C

 

 

 

 

MOVE

 

ITEM

 

K2

 

 

 

 

 

 

 

C

 

KEY

 

 

CHAIN

 

ORDDTLL

 

 

 

 

 

 

99

 

 

 

 

 

 

Figure

143.

(Part 2 of 2). Using Data Description Specifications to Define the Access Pa

(Composite

Key)

for

an

Indexed

File

 

 

 

 

 

 

 

 

When the DDS specifies a composite key, you must build a search arg program to CHAIN to the file. (A KLIST cannot be used for a program-d file.) One way is to create a data structure (using definition spec fields equal to the key fields defined in the DDS. Then, in the cal subfields equal to the value of the key fields, and use the data-st the search argument in the CHAIN operation.

In this

example, the MOVE operations set

the subfields K1 and K2 equ

value

of

ORDER and ITEM, respectively. The

data-structure name (KEY) is

used

as

the search argument in the CHAIN

operation.

Sequential File

Sequential files are files where the order of the records in the f order the records are placed in the file (that is, in arrival seque the tenth record placed in the file occupies the tenth record posit

Sequential

files

can be

processed randomly by relative record number,

utively,

or

by

a

record-address

file. You can use either the SETLL o

tion code

to set

limits

on the

file.

Record Address File

You can use a record-address file to process another file. A record contain (1) limits records that are used to process a file sequentia

(2)relative record numbers that are used to process a file by rel

numbers. The record-address file itself must be processed sequentially

A record-address file is identified by an R in position 18 of

the

ifications. If the record-address file contains

relative

record

number

must

contain a T. The

name

of the file to

be

processed

by

the

rec

must

be specified on

the

file description

specification.

You

identify

keyword RAFDATA( file-name).

290 ILE RPG for AS/400 Programmer's Guide

Page 313 Page 315
Page 314
Image 314
IBM AS/400 manual Sequential File, Record Address File, 10AIDISK, Move Order KEY Chain
Page 313 Page 315

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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