Are you going to attend the Oracle Database Interview? If you are a beginner or having some experience, then preparation is key to success. Oracle is widely used in a lot of organizations, so having a good knowledge of it can really set your career apart. This blog will cover the top 20 most common Oracle Database Interview Questions with answers, which will help you to crack the interview and get your dream job. Now interviewers don't just ask theoretical questions but are now more focused on scenario based questions, so here we have compiled questions with real scenario based questions so you get everything in one guide.
10 Oracle Database Interview Questions for Freshers
The following are the best top 10 Oracle Database Interview Questions that are generally asked in interviews, so preparing these can help you ace the interview-
Q1. What is the difference between SQL and PL/SQL?
A. SQL is used in databases to perform simple tasks such as selecting, inserting new records, and deleting. With the help of PL/SQL, program logic can be written. This is the extended version of SQL, which has all the features of SQL/ Query with added procedural features.
2. Can a table exist without a primary key? What problems might arise?
A. Yes, a table can be created without a primary key, but this creates several problems and makes the data less reliable. The chances of data duplication increase in this type of table, and it will also be difficult to build a relationship between two tables, as this process is done by a foreign key, which completely relies on the primary key.
Q3. Can you tell me what a foreign key is?
A. Foreign keys create relationships between tables, pointing to a primary key elsewhere to block invalid entries.
Q4. What is the purpose of an index?
A. Oracle is used to search data in a database. It is very similar to the index in a book, which helps us to find specific content quickly.
Q5. How would you describe a view?
A. A view is used to see the data from one or more tables; it is like a virtual table, you can see the information in any row or column without actually making any changes in the real table. It is created using a SELECT query.
Q6. What are constraints in Oracle Database?
A. In Oracle, constraints such as PRIMARY KEY, FOREIGN KEY, UNIQUE, and CHECK act as rules to maintain data reliability and prevent human errors.
Q7. What is a join, and why do we use it?
A. A Join is the way of combining data between two tables with the help of the primary key of one table and the foreign key of another table. We use this to extract data from different tables at once, which helps us to create more comprehensive reports, summaries, or insights.
Q8. What is a database transaction?
A. A database transaction is a set of one or more SQL operations that are executed as a single unit of work.
Q9. Can you explain the WHERE vs HAVING clause?
A. WHERE filters rows before grouping. HAVING filters grouped data after aggregation. HAVING is used with GROUP BY.
Q10. Why do organizations prefer Oracle Database?
A. Companies these days rely on the Oracle database because of its performance, security features, and strong support.
5 Oracle Database Interview Questions for Experienced Professionals
Q1. What happens internally when a user commits for a transaction?
A. When a user commits a transaction, it means they want to save all changes made during that transaction in the database. Then DBMS saves data and performs several steps and ensures data integrity, consistency, and durability.
Q2. How do you improve query performance in Oracle?
A. To improve the query performance, I follow a simple strategy. First, I create indexes on commonly searched columns. Then I will write the simple queries, which will avoid unnecessary columns. After that, I will fetch the data I need, and in that, I will use joins and views carefully to avoid any problems. Once the table design is checked I will finalize the query using EXPLAIN PLAN.
Q3. How do you handle locking and concurrency in Oracle?
A. To handle locking and concurrency in Oracle, I use row-level locks. This is the perfect method to lock the specific row, not an entire table. While concurrency is handled with the help of multiversioning, it is a mechanism of Oracle so that any user can easily read the data without being blocked; it is called a read-consistent view.
Q4. What is the difference between redo logs and undo data?
A. The redo logs are done in the database to record all changes, which means it stores all data that is made to the database. The main purpose of this is crash recovery. On the other hand, undo is used to restore the data before any changes are made. It rolls back the uncommitted changes.
Q5. How do you identify and troubleshoot performance issues?
A. I would start by monitoring the database to find the flow of running queries using Automatic Workload Repository (AWR) reports. Then, my next step would be using EXPLAIN PLAN or SQL Trace to analyse the query. After analysing, I will be tuning the SQL and schema, such as creating proper indexes. I will also be checking hardware resources like CPU, memory, to make sure that they are not limited factors. In the end, I will implement best practices, like minimizing unnecessary data retrieval, using bind variables, and keeping statistics up to date.
5 Scenario-Based Oracle Database Interview Questions
In 2026, companies are now focusing more on scenario-based questions rather than theoretical ones. The following are the top five Oracle Database Interview Questions that are based on real problems-
Q1. A critical query that normally runs in seconds is suddenly taking minutes. How would you troubleshoot this?
A. First, I would check the execution plan to see if Oracle changed the access path (for example, index scan vs full table scan). Then I’d verify if table and index statistics are up to date. I’d also review recent changes such as new indexes, schema changes, or data growth. If needed, I’d analyze wait events and AWR/ASH reports to identify bottlenecks like I/O or locking. The goal is to find what changed and correct it.
Q2. A table is growing rapidly and affecting performance. How would you manage this?
A. I would evaluate partitioning if the table contains large historical data. Archiving or purging old data may also help. Index optimization and proper storage planning are important. Partitioning enhances query response time and maintenance by enabling the processing of smaller portions of data.
Q3. Users report that deadlocks happen way too often. How do you deal with this?
A. Deadlocks usually result from conflicting transaction patterns. I would analyze deadlock trace files to identify the SQL statements involved. Then I’d review application logic to ensure consistent locking order and timely commits. Fixing transaction design is more effective than just adjusting database settings.
Q4. You notice excessive redo generation impacting performance. What might be the cause?
A. Heavy DML operations, frequent commits, or inefficient batch processing can generate high redo. I’d review application behavior, commit frequency, and indexing strategy. Optimizing transactions and reducing unnecessary updates can lower redo generation.
Q5. A report query scanning millions of rows runs slowly. How would you optimize it?
A. I’d look at the use of indexes, partition pruning, rewriting the query, and materialized views if applicable. It is important to minimize the I/O and the number of full table scans. Parallel processing can be good for large analytical queries at times.
Interview Preparation Tips for Oracle DBA Roles
Understand Basic Concepts: Having a strong grasp of the basics is crucial, as even for freshers or sometimes experienced candidates, interviewers often ask fundamental questions.
Practice queries: Before interviewing, hands-on practice with core SQL and PL/SQL queries gives you a solid grasp of their execution.
Get Hands-On Practice: It is suggested to have hands-on practice on Oracle tools and know how basic tasks are done.
Know the Company: It is advised to research the company you are going to interview. Connect with a current employee over LinkedIn.
Be Familiar with Latest Oracle Features: Oracle is continuously evolving, so it’s important to stay up to date with the latest features and versions.
Conclusion
Passing an interview is not only knowledge-oriented but also reflects your complete personality, from your CV to your problem-solving approach. At
Srijan Institute, we not only make you learn the technical skills but also provide you with complete placement support to assist you in the interview and to get your dream job. Enroll in our Oracle classes now and receive all the assistance you need to succeed!
FAQs Related to Oracle Database Interview
Q1. How to prepare for an Oracle DBA interview?
A. Start from the basic concepts of database and practice Oracle queries, backup and recovery strategies, etc.
Q2. What are the types of Oracle databases?
A. There are 5 types of Oracle database, and the names of these are Single-Instance, Real Application Clusters (RAC), and Oracle Exadata.
Q3. Are Oracle interviews hard?
A. Oracle interviews can seem tough, but with a complete strategy of studying and practice, anyone can ace them. For this, Srijan Institute offers
Oracle courses online that are designed for beginners.
Q4. What is Oracle Real Application Clusters (RAC)?
A. Oracle RAC allows multiple instances to access a single database, ensuring high availability and scalability.
Q5. Where can I find Oracle interview PDFs?
A. Srijan Institute provides practice interview question PDFs in its online Oracle courses.
