Transcript Advance RPG - FVTC IT | Home

Advance RPG
Chapter 12
Subfiles
Subfiles
 Collection of records that is handled as a
unit for screen input/output (I/O).
 Deals with displaying multiple records.
 Last chapter: Entered a section number
and then display info about the section.
 This chapter: Enter a course number
and display all sections offered.
Subfiles
 Additional records layouts in DDS
 One to define a subfile record (subfile record
format)
 One to control the subfile and its display
(subfile Control format)
Subfiles
 Subfile Record Format:
 Describes the fields that are to appear on
the screen. (If same as PF you can REF)
 Must have SFL in record level keyword
 Subfile Control Record Format:
 Must immediately follow the above.
 Controls the display of the subfile records
through the use of special record-level
keywords.
Subfile
 Subfile Control Record Format:
 SFLCTL: (Control) Identifies a record as the
subfile control record for subfile named.
 SFLDSP: (Display) If keyword is active,
subfile will display when control record format
is displayed.
 SFLPAG: (Page) Defines how many records
are displayed at one time on the screen.
 SFLSIZ: (Size) Should be => SFLPAG.
System will handle paging if it exceeds one
screen.
Subfile
 Subfile Control Record Format
 Optional Records Level Keywords:
 SFLDSPCTL: (Subfile Display Control) enables
the display of any output fields or constants
described within the control record format.
 SFLCLR: (Subfile Clear) If active the subfile is
cleared of all records displaying. Indicator is
required for this.
Subfile Loading
Techniques
 Loading the Entire Subfile
 Loading the Subfile a Page at a Time
 Variation 1: Subfile size one > than page
 Variation 2: Subfile size much bigger than
page
 Variation 3: Subfile size = page
Subfile Loading
Techniques
 Loading the Entire Subfile
 Size is set to hold the maximum number of
records, all records are loaded into the
subfile before anything is displayed.
 Easiest to code, but you have the slowest
initial response. Subsequent paging is very
fast.
 Inappropriate if you have a large number of
records and the user will not wait to see
them all.
Subfile Loading
Techniques
 File Spec Changes (p. 278)
 Code (p. 279)
Subfile Loading Techniques
 Variation 1: Subfile size one greater than
page
 Loads subfile one page at a time based on
user’s request for additional pages.
 New keywords:
 PAGEDOWN, ROLLUP
 SFLEND
 If off, the system displays a plus sign.
 If on, it is not displayed.
 SFLRCDNBR
Subfile Loading Techniques
 Variation 2: Size much Bigger than Page
 Also builds subfile one page at a time.
 Doesn’t have to allocate additional space in
subfile before loading.
 Slight changes to display file:
 Subsiz
 Pagedown moved to SFLSECT record format.
 RPG code remains the same.
Subfile Loading Techniques
 Variation 3: Subfile size equals page
 Appropriate for scrolling through a large
number of records.
 Response time is consistant.
 Subfile only stores one page of information.
 DDS changes are minimal.
 RPG changes are great.
 Subfile must be cleared before every display.
 Load next 15 records or start at the beginning.
ReadC Operation
 READC (Read Next Changed Record)
 Generally used with a loop, reads only those
records from a subfile that were changed
during a prior EXFMT operation.
Subfile Loading Techniques
Subfile Loading
Techniques
Subfile Loading
Techniques