IBM AS/400 manual Relative-Record-Number Processing, Methods for Processing Disk Files

Methods for Processing Disk Files

*****************************************************************

*	PROGRAM NAME:	ESWLIM2		*
* RELATED FILES:		EMPMST	(Physical File)	*
*		LIMITS	(Physical File)	*
*		PRINT	(Printer File)	*
*	DESCRIPTION:	This program shows the processing of an		*
*		externally described file sequentially		*
*		within limits.		*
*		This program prints out information for the		*
*		employees whose employee numbers are within		*
*		the limits given in the file LIMITS.		*

*****************************************************************

FLIMITS	IR	F	6	3	DISK	RAFDATA(EMPMST)
FEMPMST	IP	E		L	K DISK
FPRINT	O	F	80		PRINTER

*Input Specifications are optional for an externally desc￿ribed

*file. Here, *IN01 is defined as the record-identifying

*indicator for the record-format EMPREC to control the

*processing of this record.

IEMPREC		01
OPRINT	H	1P	1
O			12	'SERIAL #'
O			22	'NAME'
O			45	'DEPT'
O			56	'TYPE'
O	D	01	1
O		ENUM	10
O		ENAME	35
O		EDEPT	45
O		ETYPE	55
O*

Figure 154. Sequential-within-Limits Processing of a Program-Described File

Relative-Record-Number Processing

Random

input

or

update processing

by

relative

record number

applies

dural files only. The desired record is accessed by the

CHAIN

ope

Relative

record

numbers

identify

the

positions

of

the

records

relat

ning

of

the file. For example, the relative record numbers of the

seventh

records are 1, 5, and 7, respectively.

For

an

externally

described

file,

input

or

update

processing

by

rel

number

is

determined by

a blank

in

position

34

of

the

file

descrip

and the use of the CHAIN operation

code.

Output

processing

by

rela

number

is determined by a blank

in

position

34

and

the

use

of

the

on

the

file

description

specification

line

for

the

file.

Use the RECNO keyword on a file

description specifications

to

speci

field

that contains the relative record number that specifies

where

to

be

added to this file. The RECNO field must be defined as num

decimal

positions. The field length must be large enough

to

contain

t

record

number

for

the

file.

A RECNO

field

must

be

specified

if

ne

be

placed

in

the

file

by

using

output

specifications

or a

WRITE

o

Chapter 16. Accessing Database 303Files