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Introduction to J2EE Interview Questions And Answers

So you have finally found your dream job in J2EE but are wondering how to crack the 2023 J2EE Interview and what the probable J2EE Interview Questions could be. Every interview is different, and the scope of a job is different too. Keeping this in mind, we have designed the most common J2EE Interview Questions and Answers to help you get success in your interview.

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Below are the top J2EE Interview Questions that are asked frequently in an interview; these Top interview questions are divided into parts which are as follows:

Part 1 – J2EE Interview Questions (Basic)

This first part covers basic J2EE interview questions and answers.

1. What is J2EE? Name its components and client types.

J2EE stands for Java 2 Enterprise edition. Its functionality includes the development of multiple-tier web-based applications. This platform consists of a set of services, protocols, and APIs.

Components are:

Client tier components: These are the ones that execute on the client machine

Web tier components: These get executed on the J2EE server.

Business tier components: They get executed on the J2EE server

Enterprise-level system software: They get executed on the EIS server.

J2EE Client types:

Application clients

Applets

Java web-enabled clients who use Java web start technology

Wireless clients who are based upon Mobile information device Profile popularly known as MIDP technology

2. What is MVC on struts?

The MVC, popularly known as Model-View-Controller, can be described in detail.

Model: The model is used to represent the internal workings of the system as a single entity or as a multi-Java bean entity

View: Often, Java views are constructed using JSP (Java Server Pages) technology.

Controller: This is the processor that focuses on client request receiving and delivering a new user interface set as per the request. The primary component in the framework is the “ActionServlet” servlet class.

Let us move on to the following J2EE Interview Questions.

3. What is ORM and its benefits of it?

These are the basic J2EE Interview Questions asked in an interview. ORM stands for object-relational mapping. The objects in a java class are mapped with relational database tables using metadata to describe the mapping between database and objects. It transforms the data from one object to another. The benefits include:

Maintainability: This ensures that all the code generated from ORM is well tested, and correcting the functionality is only something the developer can do.

Productivity: It ends up reducing the time for data-level access coding using automatic code creation, which is based on a defined data model tools

Performance: The code generated from the ORM is used to manage the application’s data access needs. We do not need to create any data access code; the one present is optimized to speed up the data access process.

Vendor independence: The code generated from ORM is independent of the vendor. This is done to increase the portability of the application.

4. Explain important methods such as save(), Saveorupdate(), load(), get()?

Spring is an open-source Java-based application that aims to reduce enterprise application development’s complexity. It is based on inversion controlling or dependency injection design patterns.

Creation of POJOs (Plain Old Java Objects) is done, which then facilitates development to reuse existing components.

It is possible to reduce the development cost by improving application development productivity.

Dependency injection improves the testability of the application.

It is used to improve maintainability with reduced code coupling.

The need to have an application server is minimized and works on enterprise services.

Benefits of using the Spring framework:

Spring framework allows for organizing middle-tier objects in a much more efficient way.

Properties initialization is easy.

Easy testing of components

Lightweight container

Spring framework provides the possibility of configuring management services in any runtime environment in any architectural layer.

Part 2 – J2EE Interview Questions (Advanced) 6. Describe the Servlet?

Servlets are the server-side components that are used to provide a powerful mechanism for creating server-side programs. The servlets are available in a design for many protocols. Servlet is also platform-independent and server independent. The most commonly used protocol in the servlet is HTTP. A servlet is also a pure Java object.

7. What are the different phases of the Servlet life cycle?

The different phases of the servlet life cycle are:

Class loading phase: web container is used to load the servlet class files (*.class)

Instantiation phase: The default no-arg constructor is called, and the servlet class gets instantiated.

Initialization phase: The method init() is called in this phase only once in a servlet’s lifetime. Servlet configuration is generally assigned to the servlet.

Request handling phase: This is the phase where the servlets spend maximum time. Servlets provide the services to various requests by calling service ().

Removal phase: Destroy function is used to invoke the servlet destruction. Garbage collection occurs later.

8. What are the different types of JSP tags?

There are four different types of JSP tags:

Directives

Declaration

Expressions

Scripts

9. Explain the basic and subtypes of EJBs?

—Session Beans:

Stateful session beans

Stateless session beans

–Entity Beans:

Bean-managed persistence

Container-Managed Persistence

Message-driven beans

10. What is the JSP directive?

It is a mechanism to provide metadata information to a web container about a JSP file. Different types of JSP directives are:

Page directive

Include directive

Taglib directive

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Top 10 Github Interview Questions And Answers

Introduction to GitHub Interview Questions

The following article provides an outline for GitHub Interview Questions. GitHub is one of the most asked in an interview question, because helps us to manage our code, by the help of this we can easily help in the versioning of our code. If we are working in the different teams then we can easily handle our code and avoid the conflict which can occur while working on the same thing. Also, we do not need to worry about our code, because GitHub saves our all code and its history safely. It is a web-based platform with a wide range of support available online. We can come across so many questions for GitHub while interviewing but most of them related to git only.

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Part 1 – GitHub Interview Questions (Basic)

This first part covers basic interview questions and answers:

Q1. What is GitHub Repository?

Answer:

Q2. What are Branches in GitHub?

Answer:

After certain of the repository, we can create a different version for that now. At the same time, you can have different versions of that, which can help us to work on different types of new features within the team without any conflict. Every team member creates their own branch for separate changes or new functionality to work on.

All the branches can be seen on the one the below.

Simple command to create the branch is:

Code:

git checkout -b branch_name

Output:

Q3. How to Commit Code to GitHub?

Answer:

To commit the code to the GitHub, we need to do the same step that we normally follow if we are using any other repository management platform. We can either do this by using the command shell, also we can do this via GitHub, but it is always recommending to do via any version control tool here we will use git. We can download this from their official website.

Follow the below command to commit the code to your local repository.

Code:

git commit -m "your message"

-m here is used to mention the message for the commit to understanding other developers what changes we have done for this commit.

Q4. How to Add Files to the Local Repository in GitHub?

Answer:

To add the files which we want to commit, to the remote repository, this can be also be done via the git command prompt.

For this we need to run a few commands which is as follows:

git add "your file name with full path"

Q5. How to Push Commit to the Remote Repository?

Answer:

To push changes to the remote repository, we need to run few commands also we can do the same step vi GitHub, but it is recommended to do by the use of any versioning tool. To push the changes simply means, to make our local changes available to the remote repository, which can now be used and viewed by the other developers to review or contribute as well.

Part 2 – GitHub Interview Questions (Advanced) Q6. How to Switch Branch in GitHub?

Answer:

Switch branch which simply means, to navigate from one branch to another.

By the use of command, we can do this easily by the use of a versioning tool. Also, we can do this via GitHub to see the changes in the other branches. Just we have to go to the GitHub official site and select the branch we want to move to.

Also if we want to switch the branch of code on local then can easily run the below command on the command prompt.

Code:

git checkout "your branch name"

Q7. How we can Revert the Changes on Local?

Answer:

To revert any changes or revert the file to the last changes we can use the git command also we can revert the file. Here it is recommending to do by the use of versioning tool because everything can be done by GitHub but we should not do it.

So run the below command to revert the changes to the last one we had in local.

git stash

Q8. Merge Command.

Answer:

To merge the different branches into one other we can use the GitHub interface to make it fast, we also have appreciated the git command to do so. But for the freshers and beginners to git, it will be like difficult to do it. So GitHub made this easy for us to give this option there.

Q9. How to Clone Repository from GitHub?

Answer:

The clone here means to make the exact same copy of the copy on our local system by using the URL. For this we can use the git command with the URL we want to clone. This URL can be found on the GitHub page itself. It is associated with the branch we want to clone into our local system.

Also, find the below command to clone the repository:

Code:

git clone “ url ”

Output:

Q10. Explain Git Development Process in Detail?

Answer:

Analysis

Specification

Architecture

Implementation of requirement

Testing of the functionality or application

Document the things in detail

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Top 100 Qlikview Interview Questions And Answers For 2023

Here are Qlikview interview questions and answers for fresher as well experienced candidates to get their dream job.

Qlikview Interview Questions for Freshers 1) What is QlikView?

Qlikview is a business intelligence tool which is used for converting raw data into knowledge. This software acts like a human brain that works on “association” and can go into any direction to search the answers.

2) How to create a QVD file? 3) List chart types that can be used in QlikView Admin

4) What is Trellis chart?

A trellis chart is a grid of charts. It is generally a repetition of a chart across a grid.

5) What is a Pivot table?

A pivot table is defined as a table of summary that is a table that allows you to extract the information from a large data set.

6) What is QlikView objects that have the only expression but no dimension?

QlikView objects that have the only expression but no dimension are: 1) Gauge chart, and 2) list box.

7) How to use macros in the application?

Macros can be used for verities of purposes like recording application and creating an object.

8) How to set layers in QlikView?

Layers are set on sheet object properties in the layout tab, where there are options like top, bottom, and normal, respective to the numbers 0, −1, and 1.

9) Explain the use of IntervalMatch() function.

IntervalMatch () function is used to create data buckets of various sizes.

10) What is a container?

A container object is used to keep more than one chart in the same box.

11) What are the types of Join?

Types of join are 1) Left Join, 2) Right Join, and 3) Inner Join.

12) Explain three tiers of QlikView Application

Three tiers of QlikView Application are:

Tier I: Raw data is first loaded, and then QVD (QlikView Data) is created

Tier II: QVD is transformed into a business login, and its need and data model is created.

Tier III: Reading all QVD, which are there in Tier II, and one QVW is made.

13) What are the delimited files?

A delimited file is a text file in which the data field values and data fields are separated by a semicolon, tabs, comma, etc.

14) What is inline data?

Inline data means the data set that can be defined by the developer well as load in QlikView itself.

15) Explain XML files

XML is the acronym for Extensible Markup Language. It is used to structure, store, and transport data from one system to another. This markup language is similar to HTML.

16) How to load Web files into QlikView?

QlikView developers can load web files into QlikView using the script editor. It can be achieved by going to the data tab and select the ‘Web Files’ option.

17) What are the different types of data load in QlikView?

There are seven types of data load in QlikView are: 1) Load from files, 2) Resident Load, 3) Incremental Load, 4) Inline Load, 5) Add Load, 6) Buffer Load, and 7) Binary Load.

18) How to connect a database from the script editor?

After this, they need to select a Data Source Name (DSN) from the list of available databases.

19) Define Resident Load

Resident Load means file or table which are already been loaded and is residing in the memory of QlikView.

20) What is Binary Load?

A binary load is one of the types of data loaded from QlikView file into the computer’s RAM. The data from this file is loaded from 0s and 1s.

Qlikview Interview Questions for Experienced

Now let us look at the Advanced level Qlikview Interview Questions for Experienced.

21) What is QVD file?

QVD file is defined as a collection of tables having data created in QlikView. It can be easily read or written in QlikView.

22) Explain Kurtosis() and Skew() functions

Kurtosis() and Skew() are two different types of statistical aggregate functions.

Kurtosis() function measures the peak of the curve, whereas Skew () measures the symmetry in a distribution curve.

23) Mention two types of Match() function in QlikView

Mention two types of Match() function in QlikView are: Match() and Wildmatch().

24) What is the main difference between the multi-box and list box?

A multi-box is a compressed table that shows multiple table fields, whereas the list box shows all the values of single table fields in the form of a list.

25) Explain Architecture of Qlik view

The Qlik view architecture comprises of three main components, namely

QlikView Server

Qlik View Publisher

QlikView Desktop.

All these components collectively help in designing, developing, and implement the QlikView application.

Architecture diagram QlikView

QlikView Desktop: The QlikView Desktop is a Windows-based development tool. It is used by developers to use to create the QlikView data model and GUI layout for application to use at the frontend.

QlikView Server (QVS): Applications created in the desktop version are hosted on Qlik View Server (QVS) so that users can access and use them anywhere. A QlikView server maintains communication between client/end users.

QlikView Publisher: The QlikView Publisher is an optional mobile for the QlikView server-side component. This component allows you to fetch data from a data source like standard data files, Salesforce, and load data directly into QlikView files.

QlikView User Access: QlikView User Access allows customers to access and manipulate data files. The access points for the user are mostly web browsers which can open using a desktop, mobile, laptops, etc.

26) Explain QlikView Dashboard

QlikView’s dashboard is a sheet or document that consist of various kind of sheet objects containing the load data in QlikView.

27) Mention different components of a dashboard

Various components of the dashboard are: 1) Input Boxes, 2) Texts or list box Objects, 3) Selection Boxes, 4) Charts, 5) Notes and Comments.

28) Explain the basic difference between SELECT and LOAD statements

LOAD statement is used to load data from all files, from inline data, previously loaded data, autogenerated data, etc.

On the other hand, a SELECT statement is used to load data from OLE DB or ODBC data sources.

29) Explain synthetic Keys

Synthetic keys are keys which are used when two or more tables contain more than one common column among them.

30) What is a mapping load?

Mapping load is a method of creating a mapping table that can be used for replacing field names and field values.

31) Define concatenation

Concatenation is defined as a sequence of interconnected things. Any rows or columns which are related to each other can be connected using concatenation.

32) What is the difference between QlikView Server and QlikView Publisher?

QlikView Server is a Applications created in the desktop version are hosted on Qlik View Server (QVS) so that user can access and use them anywhere. The QlikView Publisher is an optional mobile for the QlikView server-side component.

33) What are the features of Qlikview?

Features of Qlikview are:

The data association is maintained automatically.

Qlikview data is stored in memory for multiple users to offers a super-fast user experience.

Transparent reporting and Scalability with Data Integration.

Various forms of data presentation.

Fast implementation.

Unique data discovery & global search.

Secure working environment.

Visual analytics & in-direct searches.

Flexibility & integrations.

Consistent reporting.

34) What is QlikView annotation? 35) Mention date and time functions 36) What are the various types of tables in QlikView?

Different types of tables in QlikVIew are:1) Pivot table, 2) Straight table, 3) Cross table, 4) Mapping table, etc.

37) Differentiate the Let and Set options in QlikView

Let assigns a variable to value only after assigning the expression.

The set option assigns a variable to a value without assessing any expression.

38) What are the four types of CAL?

Four types of CAL are:

Usage CAL

Named CAL

Document CAL

Session CAL

39) What are Sheets in QlikView?

40) Mention ways to invoke Script Editor

There are two ways to invoke script editor:

1) The developer can use the shortcut key Ctrl + E or

2) Pressing edit script icon.

41) Define the buffer load

A buffer load is a method to create a file using a buffer prefix in the memory of Qlikview for future use.

42) Mention the types of authorization implemented at multiple levels in QlikView

The types of authorization implemented at multiple levels in QlikView are:

Data level

Column level

Sheet Level

Chart level

Document-level

43) Differentiate between QV Publisher and QV Server

QV Server is a program which is installed in a physical server with a number of CALs to users to access QV files on the server. QV Publisher is a program that gives control of all QV files and how to schedule them.

44) Explain P() and E() function in the Set analysis

Developers can use P() function to return all possible values whereas, E() function is used to return a set of all excluded values.

45) List different types of data connections are used in QlikView

Different types of connections used in QlikView are: 1) ODBC, 2) SAP, 3) OLEDB, and 4) connectors.

46) What are the uses of macros in the application?

Macros are generally used to:

To create objects.

To reload the application

47) Explain the use of the Interval match function ()

Interval match function() is used to generate data buckets of different sizes.

48) List various services of the QlikView Server Environment

Various services of QlikView Server Environment are:

QVS (QlikView Server)

QVWS (QlikView WebServer)

DSC (Directory Service Connector)

QMS (QlikView Management System)

QDS (QlikView Distribution Services)

49) What is the need of a master calendar?

The master calendar is needed to create additional date values that are not captured in the analyzed data.

50) Define aggr() Function

Aggr() is a chart function that produces a virtual table, having one expression and grouped by dimensions. The result of this function can be used by further outer aggregation function(s).

51) Explain Circular loops in QlikView

A circular loop is a concept that is created when the relationship between two tables can be established directly or through the third table.

52) What is the need for promote or demote table box property?

Promote or demote enables developers to rearrange the columns in the Table box that is shown in the sheet.

53) Mention three options that available under the rotate table functionality for data transformation

Three options that available under the Rotate table functionality for data transformation are:

1) Rotate Left,

2)Rotate Right

3) Transpose.

54) How to set the table structures of data loaded to the memory of QlikView?

Use Table viewer option available under the file menu to set the tables and their relationships.

55) Define selection indicator in QlikView document

A selection indicator indicates the type of association between data which is there in different sheet projects.

56) Explain the concept of fuzzy search in QlikView

QlikView fuzzy search can find all the values according to the degree of resemblance to the string. The same result will be displayed even if the spelling is not match character by character.

59) Mention popular ways to triggered QlikView alerts

Various popular ways to triggered QlikView alerts are1) automatically, 2) manually, and 3) external program having QlikView API.

60) Mention two ways to insert load statements into the script editor

Two ways to insert load statements into the script editor are: 1) inline, and 2) form file.

61) When to use the “Force 32 Bit” option?

“Force 32 Bit” option is used while connecting to a database using ODBC and when only provides the 32-bit driver.

62) What is the subset ratio?

The subset ratio is a ratio between the total numbers of distinct values found in the table compared to distinct values in the field whose subset ratio is needed.

63) What is the use of the ScriptErrorCount system variable?

ScriptErrorCount system variable used to get the number of statements that have caused errors during script execution.

64) Define Dimensions

Dimensions are measurements that permit information examination from different points of view.

65) What is the use of binary statements in QlikView?

The binary statement is used to load data parts of a QlikView document.

66) What is the use of the garbage option in the data transform wizard?

The garbage option in the data transform wizard is used to mark and delete the data which is not needed or jumbled.

67) How to split the data in a table vertically or horizontally

The data of the table can be split vertically or horizontally using the unwrap transformation.

68) Mention the difference between NullAsValue and NullAsNull

NullAsValue enables linking of data that are null while NullAsNull treats the null values as missing values and does not allow linking of data.

69) What is the difference between QlikView and Qlik Sense?

The difference between QlikView and Qlik Sense is:

QlikView Qlik Sense

QlikView is a hidden script. Qlik Sense can be used anywhere in code.

ETL and OLAP are supported. ETL and OLAP are not supported.

Supports SaaS/ multi-cloud platform. It does not support SaaS/ multi-cloud platform.

Data mining or analytics is not possible. Data mining or analytics is possible.

70) What is QlikView data transformation?

Data transformation is the method of changing the existing data to a new data format. It also involves filtering or adding specific values to the existing data set.

71) What is rotating tables in QlikView?

The rotating table in QlikView helps you to transpose columns in multiple directions, and they give different results.

72) Explain context cell expansion in QlikView

Context cell expansion in QlikView is used to expand the contents of one cell into several cells in the table.

73) What is the use of Fill Tab in the data transform wizard?

Fill Tab in data transform wizard is used to fill in empty cells with adjacent cell values.

The theme contains UI attributes in a single file when any new object is created, it can be load from the theme.

75) What is the main difference between the grid chart and scatter chart?

The main difference between the grid chart and Scatter chart is that scatter chart plots data points representing the combinations of expressions iterated over one or many dimensions. The grid chart is a variant of a scatter chart that plots values on the axes. It uses an expression to determine the plot symbol.

76) What is apply map?

Apply map is a script function that is used for mapping output of expression, which is loaded previously in the mapping table.

77) What are the status in the QlikView management console?

A status tab of the QlikView management console enables you to see the status of the executed tasks.

78) What are the documents in QlikView?

The document contains the subtabs for source and document folders. Source documents contain a dashboard created by the developer, and the user document folder contains a published dashboard.

79) What is users tab in QlikView?

Users tab is used to configure users and client access licenses system. It contains information regarding the QlikView server environment and various services.

80) Explain the central link table

The central link table contains a combination of existing data. It helps you to merge event dimensions.

81) Define straight table

The straight table is a table that is used at the time of sorting according to the column.

82) What are the best ways to use macros in the application?

The best way to use macros are to create objects and for reloading the application.

83) What is the major difference between subset ratio and information density?

Subset ratio is used to spot the problem in the key field association, while information density is used to know the percentage of a row that contains not null value.

84) Define fact constellation schema

Fact constellation schema is a logical database structure of data warehouse that can be designed with the help of denormalized Fact.

85) What is the difference between ODBC, OLEDB, and JDBC?

The difference between ODBC, OLEDB, and JDBC is:

ODBC OLEDB JDBC

ODBC is API for accessing DBMS OLEDB is API that allows accessing data from a wide range of sources uniformly. JDBC is API for Java that defines how a client can access the database.

The full form of ODBC is Open Database Connectivity The full form of OLEDB is Object Linking and Embedding Database. The full form of JDBC is Java Database Connectivity.

86) What is Qlik Sense?

Qlik Sense is one of the majorly used tools for data visualization and data analysis. It allows you to search and refine large data sets and thereby finding sets of data, thus finding useful insights.

87) List various Name the services managed by Qlik Management Console (QMC)

Various Name the services managed by Qlik Management Console (QMC) are:

Task management

Application management

Data monitoring

Security administration

Data connectivity

Auditing

88) What is QIX Engine?

QIX is an interactive engine which coordinates and facilitates all the major functionalities in Qlik sense like:

In-memory data calculations and data indexing.

Self-service interactions.

Start searching.

Correlate with a scheduler, applications, and repository.

89) Explain streams in Qlik Sense

A stream is a number of people having the authorization to analyze the applications which are published .applications.

90) What is Qlik master library?

Master library is a concept that helps programmers to eliminate development errors and repetition.

91) What is the use of set analysis?

Set analysis is used to define a group of data values that are different from the general settings, which are defined in the current selections.

92) What is a line chart?

The line chart is majorly used in Qlik Sense. It shows the trends over time. A chart displays measures that are on the y-axis and dimensions on the x-axis. A line chart is mainly used to track the changes.

93) What is cross table?

Cross table is a common type of table having values between two lists of header data.

94) What is the windows installer?

The Windows installer a standard for software installation, repair, removal, modification, etc.

95) Mention databases that can be connected with Qlikview

The databases that can be connected with QlikView are: 1) MySQL, 2) Oracle, 3) Progress, 4) MS Access, 5) DB2, 6) SQL Server, and 7) Informix.

96) Mention steps or ways to load web files into Qlikview

Steps to load web files into QlikView are:

Step 1) Use the script editor and go to the Data Tab.

Step 2) Select web files option.

Step 3) Paste the URL you want to load.

97) List major functions available in QlikView

Major functions available in QlikView are:

Exponential and logarithmic

Financial

Date and time

General Numeric function

Aggregation

Trigonometric and hyperbolic function

String

Range

Number Interpretation

Mapping Function

Logical function

98) Mention the types of files that can be loaded in QlikView

Types of files that can be loaded in QlikView are: 1) .html, 2) .xml, 3) .xls, 4) .CSV, 5) .kml, 6) .qvd and 7) .qvx files.

99) Why is the Unwrap function used?

The Unwrap function is used to undo the operations that are performed by the wrap () function.

These interview questions will also help in your viva(orals)

Top Db2 Interview Questions And Answers In 2023

DB2 Interview Questions and Answers

DB2 interview questions and answers explore the core concepts, practices, and complexities of DB2 to help candidates ace their next interview.

Enterprises widely use DB2, a powerful relational database management system. It enjoys widespread popularity, being one of the top 10 most used databases worldwide. Moreover, candidates with knowledge of DB2 are eligible for lucrative job opportunities. As such, the average base salary of a DB2 database administrator in the US is $90851 per year.

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Table of Contents

Introduction

DB2 Interview Questions (Basic)

DB2 Interview Questions (Advanced)

Final Thoughts

Frequently Asked Questions (FAQs)

Recommended Articles

Key Highlights

Understanding the different components and their roles in DB2 architecture is crucial to answering questions on DB2 architecture in an interview.

Knowing the syntax, usage, and performance implications of complex SQL queries can help candidates demonstrate their SQL skills.

Familiarity with various data management features in DB2, such as backup and recovery, data compression, data partitioning, and data replication, can help candidates showcase their ability to manage data effectively.

Demonstrating knowledge of performance tuning can make a candidate stand out in an interview.

Well-versed candidates in authentication, authorization, encryption, and auditing features can demonstrate their ability to maintain data security and integrity in an enterprise environment.

Part 1 – DB2 Interview Questions (Basic) Q1. What is the picture clause in DB2? How can one use it in case of the null indicator variable?

In DB2, the picture clause is used to define the format of a data item. It specifies the number of digits, the position of the decimal point, and the type of data, such as alphabetic or numeric.

The picture clause can define the format of the null indicator field in the program in the case of a null indicator variable.

The picture clause for a null indicator variable must be S9(4) COMP, which specifies that it is a signed numeric field with a length of four bytes.

The first two bytes are used to store the length of the data item, and the second two bytes are used to store a binary value indicating whether the data item is null or not.

The picture clause ensures the correct formatting of the null indicator variable, enabling the checking of null values in the data.

Q2. Explain what a DB2 deadlock is and how it can be identified.

Answer:

A DB2 deadlock occurs when two or more transactions are waiting for each other to release resources needed to complete their work. Both transactions can become blocked, preventing them from proceeding and causing the application to hang or become unresponsive.

To identify DB2 deadlocks-

Enable tracing and monitoring tools, such as the IBM Data Server Manager or the DB2 Event Monitor, to capture and analyze the events and locks that occur during a transaction. These tools can help identify the resources causing the deadlock and the transactions involved.

Another method uses the DB2 administrative views and commands, such as the SYSIBMADM.SNAPLOCK table to monitor the locking activity and identify potential deadlocks.

DB2 utilities like the db2pd command or the db2top tool can display real-time lock and transaction information.

Q3. Every RDBMS database always follows some well-defined structure for the executed SQL statement in its environment. In the case of DB2, which component is responsible for executing the SQL statement? Explain with an example.

Answer:

In DB2, the component responsible for executing SQL statements is the DB2 SQL Processor. The SQL Processor receives the SQL statement from the application and performs the following steps:

Parsing: The SQL statement is parsed to identify its structure and validate its syntax. Any errors are reported back to the application.

Binding: The SQL statement is bound to the database objects it references, such as tables and indexes. This process checks the objects’ availability, verifies the user’s permissions, and generates an execution plan for the statement.

Optimization: The DB2 Optimizer optimizes the execution plan generated during binding to determine the most efficient way to access and manipulate the data.

Execution: The DB2 Access Manager executes the optimized execution plan, retrieves the data from the database, and returns the results to the application.

For example, consider the following SQL statement:

SELECT * FROM EMPLOYEE WHERE DEPT = ‘SALES’

When this statement executes, the SQL Processor will parse it to identify the SELECT and WHERE clauses, bind it to the EMPLOYEE table, optimize the execution plan to efficiently retrieve the rows with DEPT = ‘SALES’, and execute the plan to retrieve the desired results.

Q4. What is a DB2 index, and how does it work?

Answer:

An index in DB2 is a data structure that helps speed up queries on large tables by quickly allowing the database to find the rows that match specific criteria.

DB2 can use the index to quickly find the subset of rows that match the criteria specified in the WHERE clause rather than scanning the entire table when executing a query that includes a WHERE clause.

For example, if there is a table of customer orders with millions of rows, one can create an index on the “customer_id” column to speed up those queries.

Q5. One of the common approaches in the RDBMS database is expecting the average salary for an entire organization from a specific table using the common aggregator AVG. Is there any possibility of giving some wrong average value for any common mistake? If yes, explain the mistake and how we can recover the same.

Answer:

Yes, it is possible to give a wrong average value for an organization’s salary if the table contains NULL values for the salary column.

The AVG function in SQL considers only the non-NULL values to calculate the average.

If a column contains NULL values, the AVG function will exclude those values in its calculation, which can lead to a wrong average value.

To avoid this, one can use the COALESCE function to replace NULL values with a default value (e.g., 0) before calculating the average.

Alternatively, one can use the AVG function with the OVER clause and the ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING specification to include all rows in the calculation, regardless of their NULL values. By using this approach, the average can be calculated correctly even if there are NULL values in the column.

Part 2 – DB2 Interview Questions (Advanced) Q6. Which component handles DB2 database startup and shutdown?

The component responsible for handling DB2 database startup and shutdown is the DB2 Database Manager (DBM).

DBM is responsible for starting and stopping instances of the DB2 database, which are collections of databases managed as a single unit.

DBM can be started and stopped manually using the db2start and db2stop commands or automatically using operating system facilities such as systemd or init.d.

Shutting down DBM terminates all processes and services associated with the database instance and releases any system resources allocated to it.

Q7. Explain different types of locks in the DB2 database.

Answer:

Shared lock: A shared lock allows multiple transactions to read data but prevents them from modifying it. It is used for data that does not need to be updated frequently.

Exclusive lock: An exclusive lock allows transaction access to a piece of data, preventing other transactions from reading or updating it. It is used when data needs to be updated frequently.

Update lock: An update lock is similar to a shared lock in that it allows multiple transactions to read the data but reserves the right to update the data in the future. It ensures that another transaction does not update data before the current transaction can update it.

Intent lock: An intent lock indicates the type of lock a transaction intends to use on a piece of data. It is used to simplify lock management in complex transactions.

Row-level lock: A row-level lock allows a transaction to lock a specific row in a table, preventing other transactions from accessing or updating that row. It is used when a transaction needs to update a small portion of a table.

Table-level lock: A table-level lock locks an entire table, preventing other transactions from accessing or updating any data. It is used when a transaction needs to update a large portion of a table.

Q8. Explain isolation levels. At what level can it be added?

Answer:

In DB2, one can specify the isolation level for the binding step.

DB2 defines the binding step as the compilation process on the database platform.

BIND ensures the proper compilation of Cobol programming.

It helps to DB2 optimizer for preparing the SQL statement in the executable code. 

Q9. Execution of DML statements like UPDATE, INSERT and DELETE impacts some number of rows. Which field helps to show the number of rows in SQLCA?

Answer:

To check how many rows have been impacted or updated, it is necessary to validate SQLERRD, which contains that information.

Q10. What will be the defined length of physical storage for storing the timestamp in the IBM Db2 database?

Answer:

Timestamps normally occupy 10 bytes. They store in the YYYY-MM-DD HH:MM: SS: NNNNNN format.

Final Thoughts

A thorough comprehension of database fundamentals and strong technical proficiency in SQL and data administration is necessary for DB2 interview preparation. Being familiar with the DB2 platform and related tools is also crucial. A variety of subjects, including database architecture, data modeling, database administration, performance tuning, and troubleshooting, may be covered in DB2 interview questions. Moreover, Showing that the candidate can work cooperatively with a team and solve problems is crucial. One can feel more secure and prepared to demonstrate your abilities and knowledge in a DB2 interview by studying these critical topics and rehearsing answers to typical interview questions.

Frequently Asked Questions (FAQs)

Answer: DB2 interview questions are questions that an interviewer may ask to assess a candidate’s knowledge and expertise in the DB2 database management system. Some common questions involve-

2. What are the four environments which can access DB2?

Answer: The four environments that can access DB2 are:

Application programming environment

Database administration environment

System administration environment

Operations and monitoring environment

3. What type of SQL is DB2?

Answer: DB2 uses a variant of SQL called Structured Query Language/Data System (SQL/DS).

4. What is the bind process in DB2?

Answer: DB2 uses the bind process to validate and resolve database object references in SQL statements and generate an optimized access plan for the statement. The DB2 Optimizer uses the access plan stored in the database to execute the SQL statement efficiently.

Recommended Articles

This article is an EDUCBA guide to DB2 interview questions. You can view EDUCBA’s recommended articles for more information:

Top 9 Xml Interview Questions And Answers Updated For 2023

Introduction to XML Interview Questions

Web development, programming languages, Software testing & others

Interview Questions

An interview is a formal one-on-one conversation between the interviewer and the interviewee in which the interviewer is going to ask questions to the interviewee to find someone suitable for the job which they are offering and the interviewer responds by giving information.

XML interview questions with answers:

1) Explain how XML is Extensible Markup Language?

XML is extensible means it is a meta-language so we can extend its specification to define new markup language and is also playing an important role in the exchange of a variety of data on the web.

2) What is HttpRequest in XML?

For example, if we have a web page and there is an input field when we type character in the input field the XMLHttpRequest is sent from the web page to the server and it suggests some names.

3) What is getResponseHeader() method?

The XMLHttpRequest has getResponseHeader() method which is used to return a string containing the text of a particular header value, it returns the specific header information from the response server, usually the response is parsed as text and if we want entire header information then we can use getAllResponseHeader() method. A response header contains information about length, server-type, content-type, modified-date, etc.

4) Is HTML can be replaced with XML?

None of either language can replace each other but yes XML is a good alternative for HTML because it has great features like new elements that can be defined there and it can create mark up for storing data and processing it.

5) Tell any five differences between XML and HTML?

XML describes the content only.

In XML we can make our own tags.

This is a content-oriented language.

XML has multiple outputs.

It has a standard structure for data validation.

HTML:

It describes the structure and appearance of data.

It has fix set of tags that are not able to change.

It is presentation-oriented.

It has a single output form.

It does not have data validation.

6) Why use a DTD?

DTD stands for Document Type Definition and the element of XML documents is defined by it and we can say that the structure of the document with a list of elements and attributes are defined by the DTD. We have to use DTD to validate our own data as it is working for validation in XML. It is an in-built application for sharing data independently. If we are using any application that can use a standard set of DTD to verify data that we receive outside which we want to be valid. That is why DTD is used in XML.

This tag is used to create an element node in the output document. This tag is used for putting the value of the selected node as per the Xpath expression. The XSLT is the most important part of the XSL, in another way we can say that the XSLT transform an XML source-tree into an XML tree which is a result tree, let us see the syntax of it as follow,

Where,

And the XSLT is the Extensible Stylesheet Language Transformation which is used for transforming an XML document into another format that uses Xpath to perform matching of nodes which we were used for transformation and we get another document after applying XSLT to it, and the document may be of an XML document, Html document, and text document.

8) What do you mean by nested elements in XML?

The nested elements mean the root element can be nested with one or two elements and the nesting of the element will make it easier to understand the XML document.

9) Why should we go for XML editor instead of Html?

Because XML editor allows to build error-proof document and also it is validated by schema or DTD and also XML editor can check open tags as well as close tags with validation. It also checks the color code on a syntax of XML.

Conclusion

In the above article, we explained some questions related to the XML which are may be asked in the interview by the interviewer, if you are starting to learn an extensible language like XML then this will help to measure your skills, for a good interview practice more with these questions with details.

Recommended Articles

This is a guide to XML Interview Questions. Here we discuss the Introduction, list of XML Interview Questions. You may also have a look at the following articles to learn more –

50+Interview Questions And Answers (2023)

1. What is ASP.Net?

Here are chúng tôi interview questions and answers for fresher as well as experienced candidates to get their dream job.

It is a framework developed by Microsoft on which we can develop new generation web sites using web forms(aspx), MVC, HTML, Javascript, CSS etc. Its successor of Microsoft Active Server Pages(ASP). Currently there is chúng tôi 4.0, which is used to develop web sites. There are various page extensions provided by Microsoft that are being used for web site development. Eg: aspx, asmx, ascx, ashx, cs, vb, html, XML etc.

2. What’s the use of Response.Output.Write()?

We can write formatted output using Response.Output.Write().

3. In which event of page cycle is the ViewState available?

4. What is the difference between Server.Transfer and Response.Redirect?

In Server.Transfer page processing transfers from one page to the other page without making a round-trip back to the client’s browser. This provides a faster response with a little less overhead on the server. The clients url history list or current url Server does not update in case of Server.Transfer.

Response.Redirect is used to redirect the user’s browser to another page or site. It performs trip back to the client where the client’s browser is redirected to the new page. The user’s browser history list is updated to reflect the new address.

5. From which base class all Web Forms are inherited?

Page class.

6. What are the different validators in ASP.NET?

The following are different validators in ASP.NET

Required field Validator

Range Validator

Compare Validator

Custom Validator

Regular expression Validator

Summary Validator

7. Which validator control you use if you need to make sure the values in two different controls matched?

Compare Validator control.

8. What is ViewState?

ViewState is used to retain the state of server-side objects between page post backs.

9. Where the viewstate is stored after the page postback?

ViewState is stored in a hidden field on the page at client side. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source.

10. How long the items in ViewState exists?

They exist for the life of the current page.

11. What are the different Session state management options available in ASP.NET?

In-Process

Out-of-Process.

In-Process stores the session in memory on the web server.

12. How you can add an event handler?

Using the Attributes property of server side control.

btnSubmit.Attributes.Add("onMouseOver","JavascriptCode();")

13. What is caching?

Caching is a technique used to increase performance by keeping frequently accessed data or files in memory. The request for a cached file/data will be accessed from cache instead of actual location of that file.

14. What are the different types of caching?

ASP.NET has 3 kinds of caching :

Output Caching,

Fragment Caching,

Data Caching.

15. Which type if caching will be used if we want to cache the portion of a page instead of whole page? 16. List the events in page life cycle.

8) Render

17. Can we have a web application running without web.Config file?

Yes

18. Is it possible to create web application with both webforms and mvc?

Yes. We have to include below mvc assembly references in the web forms application to create hybrid application.

System.Web.Mvc System.Web.Razor System.ComponentModel.DataAnnotations 19. Can we add code files of different languages in App_Code folder?

No. The code files must be in same language to be kept in App_code folder.

20. What is Protected Configuration?

21. Write code to send e-mail from an chúng tôi application? MailMessage mailMess = new MailMessage (); mailMess.Subject = "Test email"; mailMess.Body = "Hi This is a test mail."; SmtpMail.SmtpServer = "localhost"; SmtpMail.Send (mailMess);

MailMessage and SmtpMail are classes defined chúng tôi namespace.

22. How can we prevent browser from caching an ASPX page?

We can SetNoStore on HttpCachePolicy object exposed by the Response object’s Cache property:

Response.Cache.SetNoStore (); Response.Write (DateTime.Now.ToLongTimeString ()); 23. What is the good practice to implement validations in aspx page?

Client-side validation is the best way to validate data of a web page. It reduces the network traffic and saves server resources.

24. What are the event handlers that we can have in chúng tôi file?

Application Events: Application_Start , Application_End, Application_AcquireRequestState, Application_AuthenticateRequest, Application_AuthorizeRequest, Application_BeginRequest, Application_Disposed, Application_EndRequest, Application_Error, Application_PostRequestHandlerExecute, Application_PreRequestHandlerExecute,Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache

Session Events: Session_Start,Session_End

25. Which protocol is used to call a Web service?

HTTP Protocol

26. Can we have multiple web config files for an chúng tôi application?

27. What is the difference between web config and machine config?

Web config file is specific to a web application where as machine config is specific to a machine or server. There can be multiple web config files into an application where as we can have only one machine config file on a server.

28. Explain role based security?

Role Based Security used to implement security based on roles assigned to user groups in the organization.

Then we can allow or deny users based on their role in the organization. Windows defines several built-in groups, including Administrators, Users, and Guests.

29. What is Cross Page Posting? 30. How can we apply Themes to an chúng tôi application?

We can specify the theme in web.config file. Below is the code example to apply theme:

31. What is RedirectPermanent in ASP.Net?

RedirectPermanent Performs a permanent redirection from the requested URL to the specified URL. Once the redirection is done, it also returns 301 Moved Permanently responses.

32. What is MVC?

MVC is a framework used to create web applications. The web application base builds on Model-View-Controller pattern which separates the application logic from UI, and the input and events from the user will be controlled by the Controller.

33. Explain the working of passport authentication.

First of all it checks passport authentication cookie. If the cookie is not available then the application redirects the user to Passport Sign on page. Passport service authenticates the user details on sign on page and if valid then stores the authenticated cookie on client machine and then redirect the user to requested page

All the websites can be accessed using single login credentials. So no need to remember login credentials for each web site.

Users can maintain his/ her information in a single location.

35. What are the chúng tôi Security Controls?

36. How do you register JavaScript for webcontrols ? 37. In which event are the controls fully loaded?

Page load event.

38. what is boxing and unboxing?

Boxing is assigning a value type to reference type variable.

Unboxing is reverse of boxing ie. Assigning reference type variable to value type variable.

39. Differentiate strong typing and weak typing

In strong typing, the data types of variable are checked at compile time. On the other hand, in case of weak typing the variable data types are checked at runtime. In case of strong typing, there is no chance of compilation error. Scripts use weak typing and hence issues arises at runtime.

40. How we can force all the validation controls to run?

The Page.Validate() method is used to force all the validation controls to run and to perform validation.

41. List all templates of the Repeater control.

ItemTemplate

AlternatingltemTemplate

SeparatorTemplate

HeaderTemplate

FooterTemplate

42. List the major built-in objects in ASP.NET?

Application

Request

Response

Server

Session

Context

Trace

43. What is the appSettings Section in the web.config file?

The appSettings block in web config file sets the user-defined values for the whole application.

For example, in the following code snippet, the specified ConnectionString section is used throughout the project for database connection:

44. Which data type does the RangeValidator control support?

The data types supported by the RangeValidator control are Integer, Double, String, Currency, and Date.

45. What is the difference between an HtmlInputCheckBox control and an HtmlInputRadioButton control?

In HtmlInputCheckBoxcontrol, multiple item selection is possible whereas in HtmlInputRadioButton controls, we can select only single item from the group of items.

46. Which namespaces are necessary to create a localized application?

System.Globalization

System.Resources

47. What are the different types of cookies in ASP.NET?

Session Cookie – Resides on the client machine for a single session until the user does not log out.

Persistent Cookie – Resides on a user’s machine for a period specified for its expiry, such as 10 days, one month, and never.

48. What is the file extension of web service?

Web services have file extension .asmx..

49. What are the components of ADO.NET?

The components of chúng tôi are Dataset, Data Reader, Data Adaptor, Command, connection.

50. What is the difference between ExecuteScalar and ExecuteNonQuery?

ExecuteScalar returns output value where as ExecuteNonQuery does not return any value but the number of rows affected by the query. ExecuteScalar used for fetching a single value and ExecuteNonQuery used to execute Insert and Update statements.

These interview questions will also help in your viva(orals)

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