Top 50+ Oracle Interview Questions and Answers

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Oracle is a powerful database management system created in 1977 by Larry Ellison and his team. It began as a project to build a reliable relational database and quickly grew into one of the most trusted platforms used by large companies worldwide. Today, Oracle supports everything from banking systems to enterprise apps. It is used in roles like database administrator, backend developer, and data analyst. If you are aiming for one of these roles, preparing for Oracle interview questions is a smart first step. This guide covers 50+ questions and answers to help you succeed.

Fun Fact – Oracle solutions are trusted by over 90% of Fortune 500 companies worldwide.

What’s the Oracle Interview Experience Like?

The Oracle interview experience is well-organized and designed to assess both technical knowledge and problem-solving ability. Here’s a breakdown of what to expect.

1. Oracle Recruitment Process

It usually begins with an online application through Oracle’s career portal. If shortlisted, you will receive a call or email from the HR team for an initial screening.

2. Interview Rounds

There are typically 3–5 interview rounds depending on the role. These may include:

• Online Aptitude/Coding Test
• Technical Interviews (focused on SQL, PL/SQL, or system design)
• Managerial/Behavioral Round
• HR Round (for salary, culture fit, and formalities)

3. Interview Question Types

Here are the main types of questions asked in Oracle interviews –

• Technical: SQL, PL/SQL, architecture, tuning
• Scenario-Based: Real-world problem solving
• Behavioral: Past experiences using the STAR method
• Coding: SQL queries and PL/SQL programs
• Conceptual: Features like RAC, Data Guard, ASM
• Cloud/Tool-Based: Oracle Cloud, APEX, RMAN

Basic Oracle Interview Questions

Here are some commonly asked basic-level Oracle interview questions and answers to help you build a strong foundation for your interview.

1. What is Oracle Database?

Oracle Database is a multi-model relational database management system. It stores and retrieves data efficiently using SQL. It supports complex transactions and high availability features for enterprise use.

2. What is the difference between SQL and PL/SQL?

SQL is a query language used to interact with the database. PL/SQL is Oracle’s procedural extension of SQL that allows writing full programs, including loops and conditions, using SQL statements.

3. What are schema objects?

Schema objects are the logical structures within a database schema. These include tables, views, indexes, sequences, synonyms, procedures, functions, and packages.

4. Define tablespace in Oracle.

A tablespace is the logical storage unit in an Oracle database. It groups related logical structures and maps them to physical data files on disk.

5. What is a nested table?

A nested table is a collection type used to store multiple rows in a single column. It can hold a variable number of elements and supports operations similar to arrays.

6. Differentiate between VARCHAR and VARCHAR2.

VARCHAR is reserved for future use. VARCHAR2 is the actual type used to store variable-length character data up to 4000 bytes in SQL (up to 32767 bytes in PL/SQL).

7. How do you comment in Oracle SQL?

Use — for single-line comments. For multi-line comments, wrap the text between /* and */.

Also Read - Top 30+ PL/SQL Interview Questions and Answers

Oracle Interview Questions for Freshers

These Oracle interview questions and answers are perfect for freshers looking to start their career in database or software development roles.

8. What is a primary key vs unique key?

A primary key uniquely identifies each row in a table and cannot have NULLs. A unique key also guarantees uniqueness but allows one NULL value.

9. Explain database, tablespace, and data file hierarchy.

An Oracle database contains one or more tablespaces. Each tablespace is a logical unit made up of data files. Data files store the actual database data on disk.

10. What is the RAW datatype and its typical use?

RAW is used to store binary data in hexadecimal format. It’s useful for storing images, encrypted data, or any data Oracle should not process or convert.

11. Explain savepoint with an example.

A savepoint marks a point in a transaction. You can roll back to it without undoing the entire transaction.

SAVEPOINT save1;  

— some SQL operations  

ROLLBACK TO save1;  

12. What is a materialized view (snapshot)?

A materialized view stores the result of a query physically, unlike a normal view. It is refreshed periodically and improves performance in data warehouse setups.

13. What is SYSDATE?

SYSDATE is a built-in Oracle function. It returns the current system date and time from the database server.

Example:

SELECT SYSDATE FROM DUAL;  

Oracle Interview Questions for Experienced

This section covers advanced Oracle interview questions and answers often asked to professionals with hands-on experience in Oracle technologies.

14. How does Oracle manage memory in the SGA?

SGA (System Global Area) is a shared memory structure. It holds data like SQL execution plans, cached data blocks, and redo log info. Oracle divides SGA into components like the shared pool, buffer cache, large pool, and redo log buffer. These components help with efficient data access and query execution.

15. How do you perform backup using RMAN?

I use RMAN for both full and incremental backups. 

For example:

BACKUP DATABASE PLUS ARCHIVELOG;  

RMAN automates backup validation, cataloging, and can be integrated with a recovery catalog for centralized control.

16. How does Oracle handle deadlocks?

Oracle detects deadlocks automatically. It rolls back one of the conflicting transactions to break the cycle. Deadlocks usually happen when two sessions wait for each other’s locks.

17. Explain flashback query and flashback table.

Flashback Query retrieves past data using AS OF timestamp. Flashback Table restores a table to a past state without recovery. Useful for fixing accidental changes.

18. What are Oracle hints and how are they used?

Hints guide the optimizer to use a specific plan. They are placed in comments:

SELECT /*+ INDEX(emp emp_idx) */ * FROM emp;  

Used to override the default plan when needed.

19. Describe the ANALYZE command and when you would use it.

The ANALYZE command gathers statistics or checks for corruption. It helps with optimizer decisions and object validation.

Example:

ANALYZE TABLE emp COMPUTE STATISTICS;  

Note – Although we have covered the commonly asked oracle experience interview questions, here are a few more based on your experience level.

Oracle Interview Questions for 3 Years Experienced

• How do you optimize a slow SQL query?
• Describe a scenario where you used an index effectively.
• What project best highlights your Oracle skills?
• Tell us about a time you faced a major database issue.
• How would you migrate a schema with minimal downtime?

Oracle Interview Questions for 5 Years Experienced

• How have you managed database patching in recent roles?
• Describe your experience with performance tuning.
• What was a complex challenge you solved using PL/SQL?
• Describe working under pressure during a production outage.
• Design a backup and recovery plan for a 24/7 OLTP database.

Oracle Interview Questions for 10 Years Experienced

• How would you design a high‐availability database architecture?
• Explain Oracle multitenant architecture and its advantages.
• What is the largest Oracle environment you have managed?
• Tell us about a time a planned change went wrong and how you fixed it.
• How would you implement Oracle Data Guard with zero data loss?

Oracle Technical Interview Questions

Here are some focused Oracle interview questions and answers that test your technical knowledge of Oracle architecture.

20. Write a SQL query to find the 2nd highest salary from EMP table.

SELECT MAX(salary)  

FROM emp  

WHERE salary < (SELECT MAX(salary) FROM emp);  

21. How do you convert a string to date and vice versa—give examples.

Use TO_DATE to convert string to date:

SELECT TO_DATE(‘2025-07-03’, ‘YYYY-MM-DD’) FROM dual;  

Use TO_CHAR to convert date to string:

SELECT TO_CHAR(SYSDATE, ‘DD-Mon-YYYY’) FROM dual;  

22. Explain physical vs logical storage structures in Oracle.

Physical storage includes datafiles, control files, and redo logs. Logical storage includes tablespaces, segments, extents, and blocks. Logical structures map to physical files.

23. What are redo log files and control files used for?

Redo logs track changes for recovery after crashes. Control files store metadata like DB name, log history, and file locations.

24. What are materialized views and when should you use them?

Materialized views store query results physically. They improve performance by avoiding repeated computation. Use them in reporting or warehouse systems with large, static data.

Also Read - Top 100 SQL Query Interview Questions and Answers

Tricky Oracle Interview Questions

Let’s go through some tricky Oracle interview questions and answers that are often asked in senior-level technical interviews.

25. What is the effect of using SELECT /+ ALL_ROWS / hint?

The ALL_ROWS hint tells the optimizer to favor throughput. It is ideal for batch operations where response time is less important than total efficiency.

26. How do recursive hints appear and what do they indicate?

Recursive hints appear when Oracle internally queries its own dictionary tables. They indicate background activity, not user-written SQL, and often show up during logins or grants.

27. Explain when a view is not updatable.

A view becomes non-updatable if it uses joins, group functions, DISTINCT, GROUP BY, or set operations like UNION. These make it impossible to map changes back to base tables.

28. What are the limitations of CHECK constraints?

CHECK constraints can’t use subqueries or refer to columns in other rows or tables. They can only validate values in the same row.

29. Explain function-based indexes and their use cases.

Function-based indexes index the result of a function or expression.

Example:

CREATE INDEX idx_upper_name ON emp(UPPER(name));  

They are useful when queries use functions in WHERE clauses. They help avoid full table scans.

Oracle Coding Interview Questions

Here are some practical Oracle interview questions and answers that test your coding skills in SQL and PL/SQL.

30. Write a query to flag employees who hit quota using CASE or analytical functions.

SELECT emp_id, name, sales, quota,  

       CASE WHEN sales >= quota THEN ‘Target Met’ ELSE ‘Target Missed’ END AS status  

FROM employee;  

31. Write PL/SQL to raise an exception under certain conditions.

DECLARE  

   v_salary NUMBER := 1000;  

BEGIN  

   IF v_salary < 2000 THEN  

      RAISE_APPLICATION_ERROR(-20001, ‘Salary too low’);  

   END IF;  

END;  

32. Use rownum or ROW_NUMBER() to paginate results.

SELECT * FROM (  

   SELECT emp_id, name, ROW_NUMBER() OVER (ORDER BY emp_id) AS rn  

   FROM employee  

)  

WHERE rn BETWEEN 11 AND 20;  

33. Write a MERGE statement to synchronize two tables.

MERGE INTO target t  

USING source s  

ON (t.emp_id = s.emp_id)  

WHEN MATCHED THEN  

   UPDATE SET t.salary = s.salary  

WHEN NOT MATCHED THEN  

   INSERT (emp_id, name, salary)  

   VALUES (s.emp_id, s.name, s.salary);  

Other Important Oracle Interview Questions

Let’s go through some additional Oracle interview questions and answers that cover key topics often overlooked but crucial for interview success.

Oracle Architect Interview Questions

1. How do you design a scalable, multi-tenant Oracle environment?
2. How do you enforce resource management across multiple databases?
3. Describe your approach to setting up ASM and RAC together.
4. How do you implement disaster recovery across geographical sites?
5. How would you migrate a heavy OLTP workload to Oracle Exadata?

Oracle Query Interview Questions

1. Write a query to find duplicates in a table.
2. Demonstrate a correlated subquery vs join.
3. How do you pivot rows into columns?
4. Explain the difference between ANY and ALL operators.
5. How and when would you use scalar subqueries in SELECT list?

Oracle Cloud Interview Questions

Here are some important Oracle Analytics Cloud interview questions to help you prepare for roles involving cloud-based solutions.

1. What is Oracle Autonomous Database and how is it different?
2. How do you monitor and patch databases in OCI?
3. Explain flashback technology in a cloud setup.
4. How do you configure Data Guard on OCI?
5. Describe Oracle Cloud resource tagging and IAM roles.

Oracle Apex Interview Questions

1. What is Oracle APEX and where is it used?
2. How do you pass parameters between pages?
3. How do you secure applications in APEX?
4. What reports and charts have you built in APEX?
5. How do you manage deployment between APEX workspaces?

Also Read - Top 25+ Apex Interview Questions and Answers

Interview Questions on Oracle RAC

1. What is Oracle RAC and its benefits?
2. How do you configure a VIP and SCAN?
3. How do you troubleshoot split-brain scenarios?
4. How is cache fusion related to RAC?
5. How would you patch a live RAC cluster?

Oracle Data Integrator Interview Questions

1. What is Oracle Data Integrator (ODI)?
2. Explain Knowledge Modules and their types.
3. How do you handle error logging and recovery in ODI?
4. How do you integrate ODI with Oracle golden workflows?
5. Describe a real-time integration use case with ODI.

Oracle Data Guard Interview Questions

Here are some essential Oracle Data Guard interview questions to help you.

1. What’s the difference between physical and logical standby?
2. How do you perform a switchover and what risks are involved?
3. How do you monitor lag in Data Guard?
4. Explain Active Data Guard and how it differs from normal DG.
5. How would you design Data Guard for zero data loss?

Oracle GoldenGate Interview Questions

1. What is Oracle GoldenGate and when is it used?
2. Explain setup steps for initial replication.
3. How do you resolve conflicts in multi-master replication?
4. How do you monitor GoldenGate processes?
5. What latency issues have you handled in GG?

Oracle ASM Interview Questions

1. What is ASM and why use it?
2. Explain diskgroup and its redundancy levels.
3. How do you add or replace disks in ASM?
4. What is rebalance and how does it affect performance?
5. How do ASM and RAC interact?

Oracle Exadata Interview Questions

1. What is Oracle Exadata and its core components?
2. How does Smart Scan work?
3. When should you use storage indexing?
4. How do you monitor Exadata cell performance?
5. What’s your experience with hybrid columnar compression?

Oracle Patching Interview Questions

1. How do you apply a one-off patch?
2. How do you patch a RAC environment with minimal downtime?
3. What’s the difference between patch sets and PSU?
4. How do you rollback a failed patch?
5. How do you plan patch windows for 24/7 systems?

Oracle Data Pump Interview Questions

1. How is DATA_PUMP different from original IMP/EXP?
2. How do you perform a transportable tablespace export?
3. What is a PARALLEL parameter and when do you use it?
4. How do you remap schemas during import?
5. How would you handle network import using Data Pump?

Oracle Join Interview Questions

1. Explain inner, left, right, and full outer joins.
2. What is a cross join and when is it used?
3. How do you write a self-join?
4. When would you use a natural join?
5. How do join orders affect performance?

Interview Questions on Triggers in Oracle

1. What types of triggers are available in Oracle?
2. When would you use a BEFORE INSERT trigger?
3. How do row-level and statement-level triggers differ?
4. Can triggers call PL/SQL procedures?
5. How can triggers impact performance?

Oracle 19c Interview Questions

1. What new features are in 19c compared to earlier versions?
2. How do you upgrade from 12c/CDB to 19c?
3. What’s SQL Plan Management and why is it important?
4. How does 19c support multitenant changes?
5. What new security features were introduced in 19c?

Oracle Online Assessment Questions (MCQs)

1. What’s the maximum size of VARCHAR2 in Oracle?

a. 2000 bytes
b. 4000 bytes
c. 32767 bytes
d. Unlimited

Answer: b. 4000 bytes (for SQL; up to 32767 bytes in PL/SQL)

2. What does the ROLLBACK statement do?

a. Commits the current transaction
b. Undoes all changes since the last COMMIT
c. Saves the transaction
d. Deletes the last inserted record

Answer: b. Undoes all changes since the last COMMIT

3. Which SQL command removes all rows but retains the table structure?

a. DELETE
b. DROP
c. REMOVE
d. TRUNCATE

Answer: d. TRUNCATE

4. Which join returns only matching rows from both tables?

a. LEFT JOIN
b. RIGHT JOIN
c. FULL OUTER JOIN
d. INNER JOIN

Answer: d. INNER JOIN

5. What keyword is used to set a default value for a column?

a. INIT
b. SET
c. DEFAULT
d. ASSIGN

Answer: c. DEFAULT

6. What does the SYSDATE function return?

a. The system’s time zone
b. The current date and time
c. The installation date of Oracle
d. The database version

Answer: b. The current date and time

7. How do you alias a column in a SQL query?

a. ALIAS column_name
b. RENAME column_name
c. column_name = alias
d. column_name AS alias

Answer: d. column_name AS alias

8. Which operator is used to test if a value falls within a specific range?

a. LIKE
b. BETWEEN
c. RANGE
d. IN

Answer: b. BETWEEN

9. Which constraint prevents NULL values in a column?

a. UNIQUE
b. DEFAULT
c. NOT NULL
d. PRIMARY KEY

Answer: c. NOT NULL

10. Which function is used to concatenate strings in Oracle?

a. CONCAT()
b. JOIN()
c. MERGE()
d. UNION()

Answer: a. CONCAT()

How to prepare for an Oracle interview?

Here are some practical Oracle interview preparation tips to help you feel confident and ready.

• Understand core Oracle concepts like SQL, PL/SQL, and architecture
• Practice writing and optimizing SQL queries
• Revise real-world Oracle interview questions by role and experience
• Brush up on Data Guard, ASM, RAC for advanced roles
• Use STAR method for behavioral questions
• Review recent Oracle projects or products before the interview

Wrapping Up

With these 50+ Oracle interview questions and answers, you now have a solid base to prepare for technical, behavioral, and role-specific questions. Practice well, stay confident, and be clear with your answers.

Looking for Oracle job opportunities? Visit Hirist to find top IT jobs, including roles in Oracle technologies.

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