Oracle Apex Interview Questions and Answers

1. What is Oracle Application Express?
Ans: Complete Oracle Apex Interview Questions Oracle Application Express (also called APEX and formerly called HTML DB) is a FREE RAD web development tool. APEX is written using PL/SQL and runs completely inside of a web browser. Apex is an IDE and a run time environment. You use APEX to write web applications. Users, using their database user ID, log into APEX and run their application from a menu. With the APEX IDE, you can create forms, reports and charts. All of the normal web widgets are available: radio groups, buttons, drop down lists, date pickers, etc. You can even integrate your own JavaScript code should you need it. Output from APEX applications can be to the screen or to PDF, Excel spreadsheet, Flash, or even integrated into a web service. (Oracle apex Interview Questions and Answers)

2. clarify a couple of consideration required for the static key word in apex?
Ans: Here are a couple of considerations required for the Static keyword in Apex.

1. You cannot make an Apex class static.
2. Static is just allowed in the outer class.
The Static variables are not mainly exchanged like a View State part.
Static block and static variables keep running inside and out in which they are made in a class.
Static variables are static just to the demand’s extent.

3. what is varaince between the Ajax and Action poller?
Ans: ActionPoller is a clock in Apex that empowers an AJAX refresh demand to be sent to the server as is told by a period between the time that the software developer decides. (Company)

4. I have installed Oracle 11g Enterprise Database with a view to use the embedded APEX but dont know how to launch it?
Ans:
 Oracle apex by default while installation of oracle DB .But you need to configure access mechanism to launch APEX application.

1) Apache (Web Server)

2) Embedded PL/SQL gateway

3) Oracle Listner.

5. What are the applications of APEX?
Ans: The different types of applications of APEX are to create different types of services such as email, schedules, triggering etc., creating different web services with integration of multiple systems and different services, performing validations on multiple schema objects and customized validation rules, creating customized business processes for the unavailable features.

6. Who uses APEX?
Ans: If you are running on oracle database and you want to build rich web application 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.

7. What is the architecture of APEX?
Ans: This is the common APEX Interview Questions asked in an interview. The architecture of the APEX will involve an application server, data storage where the network will be connected to the internet and the end users and developer users will be involving in the different web server requests and compilation errors and validations. The platform application server compiles the source code into a sequence of instructions and will be interpreted by Apex interpreter. The execution of the triggers will be done by the end users. There will be no delay in the web service request to the application server platform.

8. What are the couple of limitations of save point to transaction control in apex?
Ans: Each savepoint you set against governor limit for DML proclamations.
Static variables are not returned amid a rollback. If you attempt to run the trigger once more, the static variables hold the qualities from the main run.
Each rollback represents a mark against governor limit for DML articulations. You will get a Runtime mistake if you attempt to rollback the extraordinary database circumstances.
The ID on a sobject embedded subsequent to setting a savepoint isn’t cleared after a rollback.

9. What is the present version of apex and for what reason it would be to a good idea to me?
Ans: The Beta version APEX 4.2 is available in the market a few weeks back. This new form offers numerous upgrades.

Print to PDF Users can send out their reports and screens to PDF yield.
Migrate from MS-AccessUsing the export tool and the Access Migration Workbench, you can relocate client applications to APEX.
Calendar Widget Older forms incorporated a date-book gadget yet now clients can pick between day, week, or month date-books.
Improved Page and Region Caches Caching enhances execution.
Application Builder Defaults The engineer can set defaults for wizards to diminish improvement time.

10. What are the uses of APEX?
Ans:

1. Builds professional looking web applications that are both fast and secure.
2. Runs on and lives in Oracle database. APEX framework and meta data are stored in Oracle tables.
3. It is FREE. No licensing required.
4. Fast learning curve for developers to build application.
5. Deployment of application is as simple as ‘Export and Import’ if hard coded references of values that change between environments are avoided.
6. Lot of scope for customization of application look and feel.
7. Scalable for high user volume. ASKTOM, former ORACLE METALINK (before migrated to Flash version) and MANY APPLICATIONS are built using APEX.

11. What is APEX syntax?
Ans: APEX syntax has different features such as variable declaration to store the different values in the memory. The queries will be like SOQL which will be used to execute the queries, loop statements to perform the iterations in performing the operations, flow control statements can be used to control the flow execution whether to start or stop the execution process, DML statements can be used to manipulate the data by executing the queries.

12. what is apex interface?
Ans: An interface is a group of unimplemented strategies. This will indicate the signature of the strategy, kinds of inputs that we pass the technique determine what compose is given as a yield.

13. How might you refer toa present page id in apex?
Ans: If you wish to recover or refer a required ID in the Visualforce page at that point, you can simply refer to it using a standard controller

14. What method would we able to hard delete a record utilizing an apex class by cod?
Ans: ALL ROWS keywords can be utilized to get every one of the records incorporating records in recycle bin.

15. Which platforms are supported by Oracle Application Express?
Ans: Oracle Apex works on the following operating systems:
1. Linux x86
2. Mac OS X Server
3. Linux on Power
4. Linux x86-64
5. z/Linux
6. Linux Itanium
7. Solaris x86
8. Solaris Operating System (SPARC) (64 bit)
9. Microsoft Windows (32 -bit)
10. Microsoft Windows (64 -bit Itanium)
11. Microsoft Windows (x64)
12. AIX5L
13. HP-UX PA -RISC
14. HP Tru64 UNIX (Compaq / DEC)
15. HP-UX Itanium.

16. What are the different type of apex users?
Ans: Users are divided into three primary roles developer, Workspace administrators and Instance administrators.

17. How is APEX a RAD Tool?
Ans: APEX is so tightly integrated to the database, you can prototype screens while sitting with the user. The Object Browser allows you to create database objects such as tables in addition to viewing those same objects. This allows you to create objects on the fly and then build tables around those objects. The IDE, including the above Table builder, and all applications are run within a browser. Turn-around time is immediate. Because APEX is declarative, you can easily make changes in real-time via the built-in wizards. Because APEX controls session information for you, and because you use the security framework built into the Oracle Database, you can concentration delivering applications, not on connection configuration and other typical web development time wasters.

18. Are there any limitations in using Oracle XE?
Ans: XE is free but Oracle has built certain limitations into the product.
The first limitation is memory. Oracle Database XE can address only 1GB of RAM. This limitation mainly affects.

19. How many users can access the database concurrently and how well it performs?
Ans: The second limit is that XE will only use one CPU. XE will run on a multi -CPU computer but wont scale up to use those CPUs. This functionality requires Oracle Database Standard Edition or Enterprise Edition.
The third limit is that only a single XE database can run on any given computer. You do not need a database for each application. Instead, Oracle uses the concept of schemas to separate applications.
Finally, a 4GB limit is enforced on disk space. 4GB is a huge amount of storage for most applications. You can also use APEX to link to other databases (on other servers) for more storage as needed.

20. What kind of activities you have done for apex as apex dba?
Ans:

  • setup of apex environment
  • SSL configuration
  •  USER access
  •  Security modal definition
  •  ad hoc issue and resolution
  • Patching /Performance.

21. What kind of support exists for APEX?
Ans: Application Express has a robust community to help you develop, deliver, and use APEX applications. The first stop for support would be the APEX Forum sat Oracle Technology Network. This active forum provides tips and answers from many experts both inside and outside of Oracle.
Other sites include:
THE APEX WIKI: Wikipedia for the APEX crowd.
APEX STUDIO: Community created applications available for download.
APEX MAILING LIST: Sign up for info and Q&A.
THE ORACLE APEX COMMUNITY LISTING The list is growing daily.

22. How do I separate development from production environment?
Ans: 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.

23. What are the different Collections in APEX?
Ans: The different collection data structures in APEX are Lists, Maps, and Sets. A List can have any type of data stored in it such as primitives, collections, different types of complex objects or schema objects. There will be different types of methods available in the lists to perform different operations such as to retrieve the size of the list, to clear the contents, to get the details of the list and to update, delete and add the records or values into it. The same functionalities do also exist for Set and Maps but with different functionalities.

24. What is the distinction about public an global class in apex?
Ans: The Public access modifier is not quite the same as people in general modifier in Java. The public class can be accessed inside an application or namespace. While the Global class is mainly noticeable wherever: in any of the application or the namespace. The Webservice must be proclaimed as Global so it can be accessed outside of the application. The global variable is like open modifier in Java.

25. What are the features of APEX?
Ans: The different features of APEX are strong and strict data integration to perform the execution of multiple queries and statements concurrently, strongly typed which directly refers the object schema to provide the value, easy to use syntax which was derived from the java kind of programming language, easy testing which will provide easier execution and test suite creation.

26. Where can I try APEX?
Ans: As mentioned above, you can sign up for a free account at APEX.ORACLE.COM (Oracle’s hosted Application Express site). When you sign up for an account, you identify the work area name that you want to use and identify an administrator. From there you can create applications and users just as you would on your own hardware and systems.apex.oracle.com is not intended for production systems, it is intended for exploration and testing. For additional hosting companies, check out the Oracle. These sites offer varying levels of hosting including free developer access and full application deployment.

27. How do I backup and restore an Oracle XE Database?
Ans: Backing up and restoring Oracle Database XE is based on protecting the physical files that make up the
database.

There are 6 files in C:oraclexeoradataXE: CONTROL.DBF, SYSAUX.DBF, SYSTEM.DBF, TEMP.DBF, UNDO.DBF and USER.DBF.
The control file SPFILE is in C: oraclexe app oracle product 10.2.0 server dbs.
If in ARCHIVELOG mode, the redo log files should be backed up. Two redo log files are in
C: oraclexe app oracle Vlash_recovery_areaVE ONLINELOG.
Cold back up is when you stop the database and zip up all those 9 files (in NOARCHIVEMOD). When you restore the database copy all 9 files back to the same folders.

28. What is SOQL in APEX?
Ans: This is the advanced APEX Interview Questions asked in an interview. SOQL is often called as Salesforce Object Query Language which was designed and developed to work with Salesforce Database.

29. What is the utilization of interface?
Ans: An interface takes after a class in which none of the strategies have been executed the system marks are there, yet the body of each methodology is void. To use an interface, another class must realize it by giving a body to most of the procedures contained in the interface.

Interfaces can give a layer of reflection to your code. They isolate specific execution of a system from the declaration for that procedure. In this manner, you can have unmistakable use of a methodology in perspective of your particular application.

30. What are the different data types in APEX?
Ans: The different types of data types available in APEX language are Primitive Data Type (Integer, Long, Double, Date, DateTime, ID, or Boolean and String), Collections (Lists, Maps, and Sets) and Enum Classes, Interfaces and Objects. The Primitive data type Integer can be any value of a 32-bit number and will have some range similar to that of Java programming language. A Boolean data type will have a true and false value. The Date data type can only store the date value but not the time. The Primitive data type Long can be any value of a 64-bit number and will have some range similar to that of Java programming language. The String data type is a set of characters that will be initialized within single quotes. The data type Blob also exists which stores a binary set of data. Enum is an abstract kind of data type.

31. How much does APEX Cost and where can I get it?
Ans: APEX comes pre-installed and completely integrated with Oracle Database Express Edition(XE). For all other editions of Oracle Database, Oracle Application Express comes as a free add-on that can be downloaded and installed. If you chose to “try before you buy”, or since it’s free, “try before you install”, you can also use the hosted APEX Online facility. This facility allows you to create and run complete applications just as you would on your own equipment.

32. Should static files be placed in the database?
Ans: Application Express applications may reference additional external files such as cascading style sheets (CSS), images and Javascript libraries.
These images can either be placed on the file system of the server that runs the web server or, when they are uploaded using Application Express’s application builder, can be stored inside the database.
A benefit of managing files such as images and CSS in the database with the application builder is that they can be exported and imported into another Application Express environment or workspace using only a browser.
However, storing related files in the database is recommended only when you have relatively few images and when the application is not expected to endure high request throughput.
When images, CSS and Javascript libraries are stored in the database, a database connection is established each time the browser requests one of these files.
In a high throughput application this may result in undue and unwanted strain on the database.

33. What is the distinction between apex: page messages, apex: page message, apex :message and apex : messages?
Ans: apex:PageMessages: This part shows all messages that were produced for all the components on the present page, introduced utilizing the salesforce styling. This will display both salesforce produced messages and also custom messages added to the ApexPages class.

apex:PageMessage: Apex: PageMessage is a segment that includes single message the page. This is utilized to show custom message utilizing the salesforce formatting.

apex:Message: apex: Message is utilized to show a mistake on just a particular field. It is utilized to enable developers to put handle particular mistakes in the particular area.

apex:Messages: apex: Messages is like apex: Message yet it shows all the errors.

34. distinguish between trigger new and trigger old?
Ans: This command is used to return the list of new forms of object records
It is important to keep in mind that the sObject list is only accessible in the update and delete triggers
i.e., Trigger.new is accessible before and after inserts, before and after the update.
In Trigger.new the records must be changed in before triggers.
Trigger.old:

This command is used to return the list of old variants of the sObject records.
It is important to keep in mind that the sObject list is only available in delete and update triggers.
Trigger.old is accessible in after inserting, after the update, before deleting and after updating.

35. What are the Security features in APEX?
Ans: The different security rules in APEX are enforced while sharing the data or while running the code to protect the application features and code. There are different sharing security features also to be enforced and different levels of security.

36. What is apex scheduler?
Ans: It is the essential feature which is utilized just to invoke the Apex classes to enable them to keep running at unequivocal circumstances, to start with, execute the Schedulable assemblage for the class, at that point express the calendar by using either the Schedule Apex page or the System.

37. What does the APEX development environment contain?
Ans: The Salesforce APEX development environment has different features and processes to be followed in order to successfully develop an application and also to set up and edition as per the requirement of the entity. The code can be developed either in a local developer edition or a sandbox of Salesforce. As per the standards, the code will usually be developed in Sandbox and will be deployed into production. The different operations those will be performed during the development of the code is developing the code and its compilation process, debugging the code, testing the code and application, performing the SOQL query execution and its efficiency, color coding, auto alignment and auto-completion of the build process. The main step of executing the code in Salesforce will include the login action into Salesforce sandbox or console before performing these operations.

38. What is the current version of APEX and why should I upgrade?
Ans: Beta version APEX 4.2 is released a couple of weeks back. This new version offers many enhancements. 
1. Users can chose to export their reports and screens to PDF output.
Migrate from MS-Access
2. Using an export tool and the Access Migration Workbench, you can migrate user applications to APEX.
Calendar Widget
3. Older versions included a calendar widget but now users can choose between day, week, or month calendars.
Improved Page and Region Caches  Caching improves performance.
Application Builder Defaults
4. The developer can set defaults for wizards to reduce development time (basically themes for development).The benefits of upgrading include performance enhancements and additional usability features for both the developer and the end user.

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