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What is the difference between a Physical File & a Logical?
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Answer Posted / godwin sf
Physical files hold the actual data of a database file. The data is written in arrival sequence.
Physical files are not required to have keyed fields. If a physical file has key fields, this is the order that an RPG program will read the data if the File Spec in the program indicates to read the data in keyed sequence.
Also, with a keyed field, an RPG program can CHAIN, SETLL, READE and READP.
A simple logical file is a different view of the physical file. It is actually a list of pointers to the physical file. Most of the time, a logical file is nothing more than a way of accessing the physical file with different key fields.
With the standard AS/400 supplied tools, it is hard to see the logical file. One way is to use the copy file CPYF to copy the logical file to a new physical file. Then, look at the physical file... it will be in the same order as the logical file.
The AS/400 Database is full featured. Logical files can join multiple files and select and create new fields.
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I have created a command that display Source file and library. Now i want that when i enter library name and press f4 on Source file, pgm should display all the PF- SRC's in that Library. For F4 option i have used Choice program but since only limited paramters are passed in Choice pgm i am not able to paas library name and further can't call a pgm that will display list of Source files. Below is the Code snippet for CMD type object :- CMD PROMPT('Source Scan for HUB Standard') PARM KWD(SOURCE) TYPE(*CHAR) LEN(1) RSTD(*YES) + VALUES(N A) MIN(1) + CHOICE('N,A') PARM KWD(SRCFILE) TYPE(FILE) RSTD(*NO) + PROMPT('SOURCE FILE') FILE: QUAL TYPE(*NAME) LEN(10) RSTD(*NO) EXPR (*YES) + CHOICE(*PGM) + CHOICEPGM (XXXXXLIB/YYYPGM) QUAL TYPE(*NAME) LEN(10) DFT(*LIBL) + SPCVAL((*LIBL)) EXPR(*YES) PROMPT ('Library') Below is the Choice pgm:- PGM PARM(&PARM1 &PARM2) DCL VAR(&PARM1) TYPE(*CHAR) LEN (21) DCL VAR(&PARM2) TYPE(*CHAR) LEN (2000) IF COND(%SST(&PARM1 1 10) = 'CHOICE ' *AND + %SST(&PARM1 11 10) = 'SRCFILE ' *AND + (%SST(&PARM1 21 1) = 'C' *OR %SST (&PARM1 + 21 1) = 'P')) THEN (DO) /* (%SST(&PARM1 21 1) = 'C' *OR %SST (&PARM1 + */ CHGVAR VAR(&PARM2) VALUE('Name, F4 for List') ENDDO IF COND(%SST(&PARM1 1 10) = 'CHOICE ' *AND + %SST(&PARM1 11 10) = 'SRCFILE ' *AND + %SST(&PARM1 21 1) = 'P') THEN (DO) CHGVAR VAR(&PARM2) VALUE('Name, F4 for List') CALL PGM(GTSQL) PARM ('XXXXLIB') return ENDDO Thanks in Advance for looking into.
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