Top Oracle Database Developer Interview Questions

Oracle database developers are responsible for creating or maintaining an application’s database components that use the Oracle technology stack. Oracle database developers either develop new applications or convert existing applications to run in an Oracle database environment. 

For this reason, Oracle developers work closely with the Oracle database administrators, sharing knowledge and information. An Oracle database developer has a choice of programming languages for developing applications.

  • C++
  • Java
  • COBOL
  • PL/SQL
  • Visual Basic

The full functionality of the database is available in all programming languages. All programming language-specific standards are supported. Oracle developers can choose the programming languages in which they are most proficient or one that is most suitable for a specific task. 

Top Oracle Database Developer Interview Questions

For Example, an application might use 

  • Java on the server-side to create dynamic Web pages
  • PL/SQL to implement stored procedures in the database
  • C++ to implement computationally intensive logic in the middle tier

Tools for Oracle Database Developers

Oracle provides several tools for use in developing database applications. We are going to describe some commonly used database development tools.

SQL Developer

SQL Developer is a graphical version of SQL*Plus, written in Java that supports development in SQL and PL/SQL. An Oracle database developer can use it to connect to any Oracle database schema using standard database authentication. SQL Developer enables users to:

  • Browse, create, edit, and delete schema objects
  • Execute SQL statements
  • Edit and debug PL/SQL program units
  • Manipulate and export data
  • Create and display reports
  • SQL Developer is available in the default Oracle database installation and is a free download.

Oracle Application Express

Oracle Application Express (APEX) is a Web application development tool for Oracle database developers. The tool uses built-in features such as 

  • User interface themes
  • Navigational controls
  • Form handlers
  • Flexible reports to accelerate application development

Oracle Application Express installs with the database and consists of data in tables and PL/SQL code. When you run an application, your browser sends a URL request translated into an Oracle Application Express PL/SQL call. 

After the database processes the PL/SQL, the results are relayed to the browser as HTML. This cycle happens each time you request or submit a page.

Oracle database developers can use Oracle Application Express with the embedded PL/SQL gateway. The gateway runs in the XML DB HTTP server in the database and provides the necessary infrastructure to create dynamic applications. 

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Oracle JDeveloper

Oracle JDeveloper is an integrated development environment (IDE) for building service-oriented applications using the latest industry standards for 

  • Java
  • XML
  • Web services
  • SQL

Oracle JDeveloper supports the complete software development life cycle with integrated features for

  • Modelling
  • Coding
  • Debugging
  • Testing
  • Profiling
  • Tuning
  • Deploying applications.

Oracle JDeveloper uses windows for various application development tools. For Example, Oracle database developers can use tools such as the Java Visual Editor and Component Palette when creating a Java application. In addition to these tools, JDeveloper provides a range of navigators to help database developers organize and view the contents of their projects.

Oracle JPublisher

Java Publisher (JPublisher) is a simple and convenient tool for creating Java programs that access database tables. Java code stubs generated by JDeveloper present object-relational structures in the database as Java classes. 

These classes can represent the following user-defined database entities in a Java program:

  • SQL object types
  • Object reference types
  • SQL collection types
  • PL/SQL packages

Oracle database developers can specify and customize the mapping of these entities to Java classes in a strongly typed paradigm so that a specific Java type is associated with a specific user-defined SQL type.  Oracle JPublisher can also generate classes for PL/SQL packages. These classes have wrapper methods to call the stored procedure in the package.

Oracle Developer Tools for Visual Studio .NET

Oracle Developer Tools for Visual Studio .NET is a set of application tools integrated with the Visual Studio .NET environment. These tools provide GUI access to Oracle functionality, enable the Oracle database developers to perform a wide range of application development tasks, and improve development productivity and ease of use.

Oracle Developer Tools support the programming and implementation of .NET stored procedures using Visual Basic, C#, and other .NET languages. These procedures are written in a .NET language and contain SQL or PL/SQL statements. See topics for Oracle database developers.

Oracle Database Developer Job Description

The Oracle database developer is responsible for the physical database design and development.

  • Essential Functions
  • Design Logical Data Models and their physical schema design in Oracle 11g/10g database
  • Build databases depicting the physical design
  • Create Tables, Views, Indexes, and Sequences
  • Develop PL/SQL Packages, Stored Procedures, Functions, Triggers, and SQL statements in Oracle 11g/10g
  • Manage database security – Users, Roles, Privileges, and Synonyms
  • Performance Tuning, including tuning/optimizing SQL, PL/SQL code
  • Work with XML, large objects
  • Develop routines in Oracle using SQL*Loader, and third-party vendor APIs to load/integrate data between systems.
  • Preparation of development estimates and design documents
  • Oracle Database Developer Certification and Qualifications
  • Extensive Experience in designing data models and building Databases in Oracle 11g/10g
  • Proven Development Experience in SQL and PL/SQL Programming in Oracle 11g/10g in a Unix Environment
  • Experience working with XML
  • Experience in Database Schema creation and management
  • Experience with Oracle Performance Tuning
  • Experience working with development tools like TOAD
  • Strong analytical and problem-solving skills
  • Strong verbal and written communication skills
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Top Oracle Database Developer Interview Questions

  • Question: What is Oracle, and what are its different editions?
  • Answer: Oracle is one of the popular databases provided by Oracle Corporation, which works on relational management concepts; hence, it is referred to as Oracle RDBMS. It is widely used for online transaction processing, data warehousing, and enterprise grid computing.
  • Question: How will you identify Oracle Database Software Release?
  • Answer: Oracle follows several formats for every release. For Example,
    • Release 10.1.0.1.1 can be referred to as:
    • 10: Major DB Release Number
    • 1: DB Maintenance Release Number
    • 0: Application Server Release Number
    • 1: Component Specific Release Number
    • 1: Platform Specific Release Number
  • Question: How will you differentiate between VARCHAR & VARCHAR2?
  • Answer: Both VARCHAR & VARCHAR2 are Oracle data types that store character strings of variable length. Their differences are:
    • VARCHAR can store characters up to 2000 bytes, while VARCHAR2 can store up to 4000.
    • VARCHAR will hold the space for characters defined during declaration even if all of them are not used, whereas VARCHAR2 will release the unused space.
  • Question: What is meant by RAW datatype?
  • Answer: RAW datatype is used to store variable-length binary data or byte strings.
    • The difference between RAW & VARCHAR2 data is that PL/SQL does not recognize this data type and hence, cannot do any conversions when RAW data is transferred to different systems. This data type can only be queried or inserted in a table.
  • Question: What is the difference between a Primary Key & a Unique Key?
  • Answer: Primary Key identifies each table row uniquely, while a Unique Key prevents duplicate values in a table column.
    • Given below are a few differences:
      • The primary key can be only one on the table, while unique keys can be multiple.
      • The primary key cannot hold a null value, while the unique key allows multiple null values.
      • The primary key is a clustered index, while a unique key is a non-clustered index.
  • Question: Why do we need integrity constraints in a database?
  • Answer: Integrity constraints are required to enforce business rules to maintain the integrity of the database and prevent invalid data entry into the tables. With the help of the below-mentioned constraints, relationships between the tables can be maintained.
    • Various integrity constraints are available, including Primary Key, Foreign Key, UNIQUE KEY, NOT NULL & CHECK.
  • Question: What is the use of Aggregate functions in Oracle?
  • Answer: Aggregate functions perform summary operations on a set of values to provide a single value. We use several aggregate functions in our code to perform calculations. These are:
    • AVG
    • MIN
    • MAX
    • COUNT
    • SUM
    • STDEV
  • Question: What do you understand by a database object? Can you list a few of them?
  • Answer: The object used to store the data or references in a database is known as a database object. The database consists of various DB objects such as tables, views, indexes, constraints, stored procedures, triggers, etc.
  • Question: What do you understand by database schema, and what does it hold?
  • Answer: Schema is a collection of database objects owned by a database user who can create or manipulate new objects within this schema. The schema can contain DB objects like tables, views, indexes, clusters, stored procs, functions, etc.
  • Question: What is a View, and how is it different from a table?
  • Answer: View is a user-defined database object that stores the results of an SQL query, which can reference later. Views do not store this data physically but as a virtual table; hence it can be referred to as a logical table.
    • The View is different from the table:
      • A table can hold data but not SQL query results, whereas View can save the query results, which can be used in another SQL query.
      • The table can be updated or deleted, while Views cannot be done so.
  • Question: What is meant by an index?
  • Answer: An index is a schema object created to search the data efficiently within the table. Indexes are usually created on specific columns of the table, which are accessed the most. Indexes can be clustered or non-clustered. 
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