This content originally appeared on DEV Community and was authored by Pranav Bakare
For a candidate with 3 years of experience in PL/SQL, interview questions often focus on your practical understanding and problem-solving skills using PL/SQL. Here are some scenario-based questions you might encounter:
- Error Handling and Transactions
Scenario: Suppose you have a procedure that updates multiple tables based on certain conditions. If an error occurs while updating the second table, you need to ensure that the changes to the first table are rolled back. How would you handle this scenario in PL/SQL?
Expected Response: Discuss the use of BEGIN, EXCEPTION, and COMMIT/ROLLBACK. You might need to use savepoints to handle partial rollbacks or explain how to write a procedure that ensures atomic transactions using ROLLBACK on encountering exceptions.
- Cursor Management
Scenario: You have a requirement to fetch data from a table, process each row, and insert the results into another table. However, the volume of data is large, and you need to make sure that the process handles this efficiently. How would you implement this using PL/SQL?
Expected Response: Explain how to use explicit cursors or cursor FOR loops to iterate over the data. Discuss how BULK COLLECT and FORALL can be used to improve performance by reducing context switching between SQL and PL/SQL.
- Dynamic SQL and Security
Scenario: Your team needs to create a procedure that can generate reports dynamically based on different tables and columns specified at runtime. How would you approach this requirement in PL/SQL? What security concerns might arise, and how would you mitigate them?
Expected Response: Describe the use of EXECUTE IMMEDIATE for dynamic SQL. Explain how you can use bind variables to prevent SQL injection. Discuss best practices like input validation and least privilege principle to mitigate security risks.
- Performance Tuning
Scenario: You have a PL/SQL procedure that takes too long to execute because of a complex query joining multiple tables. What steps would you take to identify and address the performance issues?
Expected Response: Discuss how to use EXPLAIN PLAN to understand query performance. Explain methods like indexing, query optimization, and reducing context switches between PL/SQL and SQL by using BULK COLLECT and FORALL. Mention any experience with tuning PL/SQL code by minimizing loops and reusing cursors.
- Data Integrity and Constraints
Scenario: You need to write a PL/SQL block to handle inserting data into a table. However, you need to ensure that certain business rules are enforced, such as ensuring no duplicate entries based on specific columns and validating that certain conditions are met before inserting. How would you implement this?
Expected Response: Explain how to use constraints at the database level (like UNIQUE, CHECK) and how to implement additional validations using PL/SQL code. Discuss the use of triggers or before insert/update procedures to enforce business rules.
- Packages and Modular Code
Scenario: You are tasked with creating a set of related procedures and functions that are used across multiple applications. How would you organize this in PL/SQL, and what are the benefits?
Expected Response: Talk about using packages to group related procedures and functions together. Explain how this can provide modularity, encapsulation, and performance benefits by reducing the need to load multiple standalone procedures.
These questions test your ability to design efficient PL/SQL solutions, handle exceptions, optimize performance, and follow best practices. Be prepared to discuss real-world scenarios where you've applied these concepts and share examples from your past projects.
This content originally appeared on DEV Community and was authored by Pranav Bakare
Pranav Bakare | Sciencx (2024-10-25T18:38:30+00:00) PL/SQL Interview questions with 3 Year of experience. Retrieved from https://www.scien.cx/2024/10/25/pl-sql-interview-questions-with-3-year-of-experience/
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