FULL-PROCEDURAL FILE PROCESSING

Full-procedural files are defined by placing the letter F into column 16 of the file specification. A typical declaration for a full procedural file is shown in Figure 11.1.

Figure 11.1: File description for a full-procedural DISK file.

Both program-described and externally described database files can be declared as full procedural. Full-procedural file processing is performed by several RPG op codes. For example, to read a record from a file, the READ operation is used. To write a new record to a file, the WRITE operation is used. Table 11.1 lists RPG op codes that can be used with full-procedural files.

Table 11.1: File-Based Op Codes

Op Code	Description
ACQ	Acquire program device.
CHAIN	Random file access by index.
COMMIT	Commitment control, commit group.
DELETE	Delete database file record.
EXCEPT	Write program-defined or externally described record format.
EXFMT	Write, then read, a workstation device-file record format.
FEOD	Reset the file "cursor." Unlock any locked records.
KFLD	Define a key field of a key list.
KLIST	Define key list.
OPEN	Open file.
POST	Retrieve and post device-specific information to a data structure.
READ	Read record.
READC	Read next changed subfile record.
READE	Read next database file record with matching index.
READP	Read previous database file record.
READPE	Read previous database file record with matching index.
REL	Release acquired program device.
ROLBK	Commitment control, roll back group.
SETGT	Set file cursor greater than the specified index.
SETLL	Set file cursor less than the specified index.
UNLOCK	Release record lock.
UPDATE	Update record.
WRITE	Write record.

In discussing file processing, several database terms are used. These terms are general to the topic of databases and specific to the AS/400 system. Here's a look at a brief glossary of file terminology:

access path: An object used to access data in a file in a specific sequence.

cross reference: A set of files containing fields for where and how information is used.

library: A directory of a group of related and unrelated objects that have been placed into a specific context.

field: In a record, one or more bytes of information that make up a single fact.

File: A directory of members and formats. Typically referred to as physical files, logical files, or join logical files, file is a generic term for database file.

member: The entity within a database file that contains the actual data. A set of fields and records.

index: See access path.

join logical file: A subset of fields and records from two or more files.

Key: See access path.

key field: A field in a physical or logical file used to determine the order of entries in an access path.

logical file: A subset of fields and records from a file.

physical file: A database file containing records of real data.

record: A horizontal line of data in a physical or logical file.

random access: A method of processing a file randomly by its access path through its key fields.

view: A subset of fields and records from a file.