Interview Questions and Answers

Ques 1. What is Oracle Application Express?

Oracle Application Express (APEX) is a low-code development platform that enables you to build scalable, secure enterprise apps, with world-class features, that can be deployed anywhere.

Ques 2. How do you create a new application in Oracle Application Express?

You can create a new application in Oracle Application Express by going to the "Application Builder" section and clicking on the "Create" button.

Ques 3. Can you explain how to install Oracle Application Express(APEX) on an existing database?

There are two ways: On-Premise and Cloud.

On-Premise: The first thing you need to do is download the Oracle Application Express installer from the Oracle website. Once you have the installer, you will need to unzip it and then run the setup.exe file. After accepting the terms and conditions, you will need to choose the installation type. There are two options: using the Oracle Database Express Edition or using an existing Oracle database. If you choose to use an existing database, you will need to provide the hostname, port, and SID of the database. After the installation is complete, you will need to run the configuration script. This will create the necessary tables and users for Oracle Application Express.

Cloud: Open the existing autonomous database in Oracle Cloud Infrastructure. Open 'All Database Actions' where you can see the 'APEX' option. Click on 'APEX' where it will first ask to login as admin. Once you login, it will ask to create an workspace. Under that workspace, you can create users. Then logout from admin and login as developer user with the created workspace. Once you are logged-in, you can create applications.

Ques 4. Can you explain the difference between shared and local workspaces in Oracle Application Express?

Shared workspaces are those that are accessible to all users of the application, while local workspaces are only accessible to the user who created them. In a shared workspace, all users have the same privileges, while in a local workspace, the creator of the workspace has full control over who can access it and what they can do.

Ques 5. Can you give me some examples of real-world applications that use Oracle Application Express?

There are a number of real-world applications that use Oracle Application Express. Some examples include the United States Department of Veterans Affairs, NASA, and the National Weather Service and Oracle's own multiple products.

Ques 6. What are the main features offered by Oracle Application Express?

• Oracle Application Express (APEX) is a low-code development platform that enables you to build scalable, secure enterprise apps, with world-class features, that can be deployed anywhere.
• Oracle Apex is a powerful and user-friendly tool that allows developers to create web-based applications quickly and easily. Its integration with Oracle Database, built-in security features, and customizable themes make it a cost-effective and scalable option for businesses looking to create custom applications.
• Oracle APEX is designed to build web apps that are highly secure out of the box. In a world of constantly changing web standards and increasingly resourceful attackers finding new ways to hack sites, our focus on security means that your applications stay protected.
• APEX eliminates mapping between relational and application objects.
• APEX eliminates remote procedure call complexity.
• APEX eliminates proliferation of database connections.
• APEX eliminates middle-tier application logic.

Ques 7. Does APEX work with non-Oracle databases?

No. It will work only with Oracle database.

Ques 8. What are the skills required for APEX Developers?

SQL, PL/SQL is essential. HTML, CSS, and JavaScript are good to have skills to understand and customize look and feel (themes, templates, …. ).

Ques 9. Why would you want to build a mobile app using Oracle Application Express?

Oracle Application Express is a great tool for building mobile apps because it is very user-friendly and easy to use. Additionally, it offers a lot of flexibility in terms of how you can design and build your app.

Ques 10. How does Oracle Application Express compare with other frameworks like Ruby on Rails or Django?

Oracle Application Express is a web application development framework that is similar to frameworks like Ruby on Rails or Django. It is used to develop web applications using Oracle databases. It includes a number of features that make it unique, such as the ability to automatically generate forms based on database tables, and the ability to easily integrate with Oracle databases.

Ques 11. Is it possible to migrate the code from one workspace to another? If yes, then how?

Yes, it is possible to migrate the code from one workspace to another. In order to do this, you will need to use the Export/Import feature within Oracle Application Express.

Ques 12. How can you keep your development environment up-to-date with regard to security patches?

You can keep your development environment up-to-date with regard to security patches by regularly checking for updates from Oracle and applying them as necessary. You can also subscribe to Oracle’s security mailing list to receive notifications of new security patches as they are released.

Ques 13. What are the key differences between SQL Workshop and Apex Workspace?

• SQL Workshop is a tool for working with SQL databases, while Apex Workspace is a tool for working with Oracle Application Express applications.
• SQL Workshop provides a user interface for running SQL queries and commands, while Apex Workspace provides a user interface for developing and managing Oracle Application Express applications.

Ques 14. What is the usage of the apex_util package in Oracle APEX?

The apex_util package is used for a variety of tasks related to Oracle Application Express, including retrieving session information, generating HTML, and creating email messages etc.

Ques 15. How do you design a responsive page using Oracle Application Express?

In order to design a responsive page using Oracle Application Express, you will need to use the fluid grid layout. This will allow you to create a page that will resize itself based on the size of the device that it is being viewed on.

Ques 16. Are there any performance issues when thousands of users access a single instance of Oracle?

There are no known performance issues when thousands of users access a single instance of Oracle. In fact, Oracle is designed to handle large numbers of users and transactions as it is scalable by default.

Ques 17. What are some best practices for developing web apps using Oracle Application Express (APEX)?

Some best practices for developing web apps using Oracle Application Express include using the built-in security features to control access to the app, using bind variables to avoid SQL injection attacks, and using the built-in report generation features to generate reports on app usage.

Ques 18. What are the different types of reports available in Oracle Application Express?

There are four different types of reports available in Oracle Application Express: Classic Reports, Interactive Reports, Matrix Reports, and Pivot Grid Reports.

Ques 19. What is a break field in context of reporting in Oracle Application Express?

A break field is a field that is used to break up data in a report. For example, if you have a report that contains data for multiple years, you could use a break field to break up the data by year. This would allow you to easily see the data for each year separately.

Ques 20. What kind of activities you have done for APEX as APEX DBA?

1. Setup of apex environment
2. SSL configuration
3. USER access
4. Security modal definition
5. ad hoc issue and resolution
6. Patching/Performance

Ques 21. Who uses APEX?

If you are running on an oracle database and you want to build rich web applications with reports, forms, charts, drill downs and dashboards with limited Java experienced developers in a short time frame, Oracle APEX is the most likely candidate for consideration.

Ques 22. How does APEX Architecture work?

APEX is installed on Oracle database (above 9.2 version), starting from Oracle 11g it comes pre-installed with the database. It is comprised of metadata in tables, pl/SQL code, and extensive JavaScript APIs.
The URL request from the browser is translated into appropriate APEX PL/SQL call by either Oracle HTTP Server (Apache) with mod_plsql plugin or Embedded PL/SQL Gateway. This varies by the type of APEX installation on the oracle database. After the data is processed, results are relayed back to the browser as HTML. This cycle happens each time a user requests or submits a page. The application session state is maintained in database tables.
APEX installation can be done in two ways. DBAs are more concerned about it than developers. But this determines how the URL is translated.

Ques 23. How do I separate development from production environment?

• Depending on requirements for the availability of the application, the size of the user population, and other factors you can decide how to divide the development environment from the production environment.
• For certain applications, it is acceptable to combine the development server with the deployment server, as long as the end users understand that sometimes the application is not available.
• Other applications may require two (development and production) or even three (development, test, and production) servers.
• In Application Express applications can be moved from environment to environment using an export and import facility for application definitions.
• With one server available to run the database and Application Express, you can still separate the development version of an application from its production version by using two workspaces accessing separate schemas.
• In this case, one workspace will be used by developers and the other will be the workspace in which the application is deployed in production. We will add a few more Oracle Apex Interview Questions soon.