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Information Technology

Oracle Developer Interview Questions and Answers

Oracle developers design, implement, and maintain database solutions using Oracle's PL/SQL, SQL, and tools like Oracle Forms and Reports. They focus on data integrity, performance, and security in enterprise environments.

20 practice questions with explanations and sample answers.

  1. 1. Why do you specialise in Oracle development?

    What the interviewer is looking for

    Show appreciation for robustness and enterprise features.

    Sample answer

    Oracle is a powerful, enterprise‑grade database with advanced features. I enjoy the challenge of optimising complex queries and building robust PL/SQL applications.

  2. 2. Explain the difference between SQL and PL/SQL.

    What the interviewer is looking for

    SQL is declarative, PL/SQL is procedural.

    Sample answer

    SQL is used for querying and manipulating data; PL/SQL is a procedural language that includes loops, conditions, and error handling for business logic inside the database.

  3. 3. What is the purpose of a stored procedure versus a function?

    What the interviewer is looking for

    Procedures do not return values; functions do.

    Sample answer

    Stored procedures perform actions (e.g., update) but do not return values. Functions return a value and can be used in SQL expressions.

  4. 4. Describe a time you optimised a slow SQL query in Oracle.

    What the interviewer is looking for

    Use explain plan, indexes, and hints.

    Sample answer

    I used EXPLAIN PLAN and added a composite index, reducing the query time from 15 seconds to under 1 second.

  5. 5. What is your experience with Oracle triggers and their use cases?

    What the interviewer is looking for

    Auditing, validation, and automation.

    Sample answer

    I use triggers for auditing changes, enforcing complex business rules, and automatically populating derived columns.

  6. 6. How do you handle bulk data processing in PL/SQL (BULK COLLECT, FORALL)?

    What the interviewer is looking for

    Improve performance with bulk operations.

    Sample answer

    I use BULK COLLECT to fetch data in batches and FORALL to perform DML operations in bulk, reducing context switches.

  7. 7. What is the difference between DELETE, TRUNCATE, and DROP?

    What the interviewer is looking for

    Define scope and recoverability.

    Sample answer

    DELETE removes rows (can be rolled back), TRUNCATE removes all rows (fast, cannot be rolled back), DROP removes the entire table.

  8. 8. Describe your experience with Oracle partitioning and why it is used.

    What the interviewer is looking for

    Improve performance and manageability.

    Sample answer

    I have partitioned large tables by date to improve query performance and simplify data archiving.

  9. 9. What is the purpose of indexes and what types have you used?

    What the interviewer is looking for

    B‑tree, bitmap, function‑based.

    Sample answer

    Indexes speed up data retrieval. I use B‑tree indexes for primary keys and bitmap indexes for low‑cardinality columns.

  10. 10. How do you manage error handling in PL/SQL (EXCEPTION blocks)?

    What the interviewer is looking for

    Catch and handle exceptions.

    Sample answer

    I use EXCEPTION blocks to catch specific exceptions like NO_DATA_FOUND and DUP_VAL_ON_INDEX, logging errors and rolling back as needed.

  11. 11. What is the role of the Oracle Optimizer and how do you influence it?

    What the interviewer is looking for

    Use statistics and hints.

    Sample answer

    The optimizer chooses the execution plan. I use DBMS_STATS to update statistics and hints to influence the plan when necessary.

  12. 12. Describe a time you worked with Oracle Forms or Reports.

    What the interviewer is looking for

    Mention legacy or modern tools.

    Sample answer

    I have maintained Oracle Forms applications and used Oracle Reports for generating PDF and HTML reports.

  13. 13. What is the difference between ROWNUM and ROW_NUMBER()?

    What the interviewer is looking for

    ROWNUM is pseudo‑column; ROW_NUMBER is analytical.

    Sample answer

    ROWNUM assigns sequential numbers to rows in the order they are returned. ROW_NUMBER() is an analytic function used for ranking within partitions.

  14. 14. How do you implement security in an Oracle database?

    What the interviewer is looking for

    Users, roles, and privileges.

    Sample answer

    I create users, assign roles, and grant minimal privileges. I also use VPD (Virtual Private Database) for row‑level security.

  15. 15. What is your experience with Oracle Data Pump or Export/Import?

    What the interviewer is looking for

    Migration and backup.

    Sample answer

    I use Data Pump for full and partial database exports and imports, especially for migrations and schema refreshes.

  16. 16. How do you monitor and improve database performance?

    What the interviewer is looking for

    Use AWR, ADDM, and SQL Tuning Advisor.

    Sample answer

    I generate AWR reports, use ADDM for recommendations, and run SQL Tuning Advisor to fix problematic queries.

  17. 17. What is the purpose of materialised views in Oracle?

    What the interviewer is looking for

    Pre‑computed results for performance.

    Sample answer

    Materialised views store query results physically, improving performance for complex, read‑heavy queries.

  18. 18. Describe a time you resolved a deadlock issue.

    What the interviewer is looking for

    Investigate and redesign.

    Sample answer

    I used the V$LOCK view to identify the sessions involved and redesigned the transaction order to prevent the deadlock.

  19. 19. What is your experience with Oracle cloud or Exadata?

    What the interviewer is looking for

    If applicable.

    Sample answer

    I have experience with Oracle Cloud Infrastructure (OCI) and basic Exadata performance features.

  20. 20. Why do you want to work for our database team?

    What the interviewer is looking for

    Mention their data scale or environment.

    Sample answer

    Your organisation has a massive data footprint. I want to contribute to its reliability and performance.

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