Monday, 6 August 2012

ibm as400 interview questions answers


IBM AS-400 Interview Questions-->4



101.What is a Logical file?
It is nothing but a logical view provided by the physical file.

102. What is Join Logical file?
Join logical file joins more than one file.The maximum of number of files  allowed to join is 32 (thirty two).  

103. What are the necessary keywords for the Join Logical file?
JDFTVAL, JFILE, JOIN, JFLD, JREF.

104. What is a Non-join logical file?
It only provides logical view based on the physical file.This is also called as regular logical file.

105.What is the necessary keyword for Non-join logical file?
PFILE (which is record level keyword)

106. How many levels are there in a Physical file?
Four levels.  They are File level, Record level, Field level, Key field level.

107.What is the use of UNIQUE keyword and what level it is defined?
It will avoid entering duplicate key values. We have to define it in a file level. 

108.At what level S,O are defined and what they will do?
S, O are to defined at key field level.The purpose Select/Omit logic is depends on the criteria (condition) given at the key field level (At function entry) it selects and omits the records. The S/O is allowed in Logical file only.

109.What is the difference between packed decimal and Zoned decimal?
Packed decimal: One digit occupies 1 byte.
Zoned decimal:   One digit occupies 2 bytes.

110.What is default data type (if you define decimals '0') in Physical file?
Packed decimal

111.  What is default data type for the fields (sub fields) defined in data structures in RPG?
Zoned decimal

112.What is the use of JDFTVAL in join logical file?
If you specify JDFTVAL at file level, even the primary file record does not match with secondary file record, the join takes place.

113. Is it possible to create a physical file without DDS?
Yes. With the help of CRTPF we can achieve this.   But we have to give record length.

114.What is a Keyed physical file?
Defining a field as a key in physical file.   Hence we can access records through the key field.

115.What is a composite key?
Defining more than one key as a key field in physical file.

116. What is arrival sequence?
The records will be accessed the way in which records are added to physical file.

117. What is the maximum number of key fields allowed defining in a physical file?
120

118. What is acronym of RPG?
Report Program Generator

119. What is the native language of AS/400?
RPG/400

120. Why RPG/400 is famous?
      * Easy to code and analyze.
      * Supports externally described files.
             
121. How many specifications are there in RPG/400? What are they?
There are seven specifications are exits in RPG/400.   They are listed below:
             
       * Header Specification
       * File Description specification
       * Extension specification
       * Line counter specification
       * Input specification
       * Calculation specification
       * Output specification

122. When do you use F-spec  Continuation line?
 * In order to refer the named record format as a subfile record format in the program.
 * In order to rename the record format of a database file in a program.
 * In order to define a named data structure as a file information data structure.  

123.What are the various types of device files?
Display files, printer files, diskette files, tape files etc. ,

124. When do you explicitly open files and close files in an RPG program?
If you specify the letter ' U ' at column 73-74, you need to be open and close files explicitly in a RPG program.

125. How do you know that records are locked?
By using a command WRKOBJLCK.

126. What is the purpose of Indicators in RPG?
In order to control the logic flow, we can use indicators in RPG.

127.  How do you read data area in an RPG program?
With the help of ‘IN’ OPCODE, we can access the data area record in to the program.

128.  What are the different types of Data Areas?
The different types of Data Areas are general data area, local data area, group data area, pip (program initialization parameter data area) data area.
         *General Data Area -   It can be created by user implicitly or explicitly
                                     It can be referred by any other jobs.
                                     It can be associated with a library.
                                     It can be created, deleted by the user.

           * Local Data Area   -    It can not be referred by any other job.
                                     It is automatically created and deleted by the system.
                                     It is not associated with any library.

          *Group Data Area    - It is automatically created and deleted by the system
                                    We can access the group data area value through clp.
                                     It is meant for group jobs.
         *Pip Data Area        -    It is meant for pre start jobs.

129.What are various techniques to pass parameters from one program to another?
PLIST, CALL, TFRCTL

130. Which single RPG OPCODE performs both SETLL and READE?
CHAIN

131. What is term CUA, SAA?
Common User Access
System Application Architecture

132.Why is AS/400 called Object Oriented Machine?
Everything on the AS/400 System that can be stored and retrieved is contained in the object.

133. What is the version of OS/400 that we have?
V4R2 (Version 4. 0 Release 2. 0)

134. What is DDM?
Distribution Data Management is a function of the OS/400 that allows an application program or user on one system to use database files stored on remote system.

135. What is an Object?
An object is any thing that exists in and occupies space in storage and on which operation can be performed.

136. How are the objects stored on AS/400?
All objects are stored on AS/400 in a single level storage.  In this method all objects are referenced by one virtual address which is translated in to a physical address whether it is an auxiliary storage or main memory.

137. What is a Library in AS/400?
A library in AS/400 is an object that serve (acts) as a repository for other objects.

138. Name few IBM supplied libraries?
QGPL, QTEMP, QSYS, QUSRTOOL, QCBL, QRPG

139.   What is library list?
 A list that indicates libraries used for the process and the order in which it has to be  searched System identifies it in *LIBL.

140. How many libraries can be there in library list?
 Total 40 (15 system and 25 application)

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