As400 Interview Questions Part 4

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We covering the core + tricky IBM i (AS400) interview concepts 👏
Here’s the next 20-question set with answers:

1. How we can check no. of records in a file using CL command?

  • Use:

DSPFD FILE(MYLIB/MYFILE) TYPE(*MBR) OUTPUT(*PRINT)

  • The report shows record count.

  • Or use RUNSQL:

RUNSQL SQL('SELECT COUNT(*) FROM MYLIB/MYFILE') COMMIT(*NONE)

2. Difference between SFLCLR and SFLINZ?

  • SFLCLR → Clears existing subfile records.

  • SFLINZ → Initializes subfile records with default values (blank/zeros).

3. Difference between fully procedural file and Primary file?

  • Fully Procedural → Program controls file access (OPEN, CLOSE, READ).

  • Primary File → Controls main program cycle (in RPG cycle, record read automatically at cycle beginning).

4. What is a Journal?

  • A system object (*JRN) used to log changes (before/after images) of database objects for recovery and auditing.

5. What is the final status of the Job?

  • OUTQ (spooled output) generated and job status = ENDED.

  • If abnormal termination, status may show as MSGW or END.

6. Difference between CHAIN and READE?

  • CHAIN → Random access by key; retrieves single matching record.

  • READE → Reads next record equal to given key value (sequential).

7. Advantage of using Externally Described files over Internally Described file?

  • Externally Described (DDS-defined):

    • Field definitions stored in file object.

    • Easier maintenance (if file changes, program recompiles automatically).

  • Internally Described:

    • Fields hardcoded in program → harder to maintain.

8. What is the output of the following?

D var1     S     5P0
D var2     S     5P1
/Free
   Var1 =  *loval;
   Var2 = *highval;
/End-Free

  • Var1 (5P0): *LOVAL = -99999

  • Var2 (5P1): *HIGHVAL = +9999.9

9. Which built-in function would you use to achieve this?

If Var1 < 0;
   Var1 = Var1 * -1;
EndIf;

  • Use %ABS(Var1) → returns absolute value.

10. What is the significance of UDATE?

  • UDATE is a reserved RPG keyword → current system date in numeric (MMDDYY) format.

  • (Obsolete; use %DATE now).

11. What is DDM?

  • Distributed Data Management.

  • Allows accessing database files located on a remote IBM i system as if local.

12. How to retrieve the attributes of a Job?

  • CL Command: DSPJOB JOB(MYJOB) or WRKJOB.

  • API: QUSRJOBI retrieves job info in programs.

13. What are system objects required for Journaling?

  • *Journal (JRN)

  • *Journal Receiver (JRNRCV)

  • Database file objects linked to journal.

14. Difference between Journaling and Commitment control?

  • Journaling → Logs changes for recovery.

  • Commitment Control → Groups operations into transactions with COMMIT/ROLLBACK.

  • Journaling is required for commitment control.

15. How to check active jobs in the system?

  • WRKACTJOB → shows active jobs by subsystem.

16. How to create a user defined command?

  • Steps:

    1. Create command definition object: CRTCMD.

    2. Define command processing program (CL/RPG).

    3. Link command to program.

17. How to lock a data area after updating it?

  • In CL: CHGDTAARA updates value; lock by DSPDTAARA with *EXCL.

  • In RPG: Use IN/OUT with *LOCK to update.

18. How to retrieve data area value in CL or RPG?

  • CL: RTVDTAARA DTAARA(MYLIB/MYAREA) RTNVAR(&VAR).

  • RPG: IN DTAARA_NAME (old RPG) or use APIs.

19. How to change data area value in CL or RPG?

  • CL: CHGDTAARA DTAARA(MYLIB/MYAREA (1 10)) VALUE('ABC').

  • RPG: OUT DTAARA_NAME.

20. What is the type and length of *LDA?

  • Local Data Area (LDA) = 1024 bytes, type = CHAR.

✅ That’s your 4th set of 20 (total = 80 Q&A so far).

AS400 interview questions | Answers with explanation 20 questions | Part4

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