8 PL/SQL Interview Questions For Experienced Professionals

By Indeed Editorial Team

Published 8 September 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Developers can query databases using the procedural language PL/SQL. This technology advances SQL and can provide more data manipulation functionality. Studying some PL/SQL questions an employer may ask you can assist you in preparing for the interview. In this article, we discuss some PL/SQL interview questions for experienced candidates with sample answers and share tips to help you better prepare for your interview.

PL/SQL Interview Questions For Experienced Professionals

Here are some PL/SQL interview questions for experienced professionals with sample answers to help you prepare effectively:

1. What do you know about PL/SQL?

When you apply for a programmer role as an experienced candidate, the hiring manager may expect you to have an understanding of the programming language and to demonstrate your experience and skill level. While answering, briefly explain PL/SQL's uses.

Example: 'PL/SQL, developed as a procedural language, is a variant of the robust database management system SQL. PL/SQL functions as an extension to SQL. It can include SQL statements and expand SQL's capabilities. The database server compiles PL/SQL program units and embeds them along with the SQL and Java programming languages.'

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2. Tell me some characteristics of PL/SQL

To write the PL/SQL code effectively, it is important for you to understand its features and commands. The hiring manager may ask you this question to determine your technical PL/SQL knowledge level.

Example: 'PL/SQL is a portable programming language, which means it is compatible with multiple programming structures and operating systems. It supports the development of web applications and servers, along with structured and object-oriented programming, enhancing its versatility. It also provides advanced security features.'

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3. What is the biggest challenge you have encountered while programming in PL/SQL and how did you overcome it?

The hiring manager may ask you this question if you manage a team of programmers and have extensive PL/SQL experience to assess whether you are able to solve problems and overcome challenges that may occur in the role. With this question, they can determine whether you can identify and resolve the technical problems. In your answer, consider mentioning both general and specific work-related issues you have resolved.

Example: 'The most challenging aspect of my previous position as a PL/SQL programmer was that the PL/SQL code requires a database to function. Occasionally, when the database went down, the code returned an error. As an administrator of the database, implementing monitoring and escalation software helped me ensure a high percentage of uptime to solve the issue.'

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4. What are the advantages of PL/SQL packages?

The hiring manager may ask you this question if you have experience working on PL/SQL projects. Besides coding, they may also assess your knowledge of PL/SQL packages and their function in the development of applications. In your response, provide an example of how PL/SQL packages improve the functionality and performance of big database systems.

Example: 'Using a PL/SQL package, we can keep all related functions and processes in a single unit. It enables the memory to load various objects and permits all code blocks to execute concurrently while decreasing traffic. These two factors contribute to performance enhancement. Using a PL/SQL package, programmers can implement an object-oriented design. Hidden PL/SQL package code allows developers to create the interface. Modifying one module within a PL/SQL package can also modify another module in the same way.'

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5. Describe joins in PL/SQL.

Administrators of databases may store enormous datasets in multiple database tables. The interviewer may ask this question to determine your familiarity with data extraction from multiple tables. You may answer by explaining joins and their use.

Example: ‘A join is a method for combining data from multiple tables into one result set. The Non-ANSI and ANSI join syntaxes allow you to join tables. Programmers often use the ANSI join syntax as it is easier to use, supports various database engines and may also provide additional functionality. The [INNER], LEFT [OUTER] and RIGHT [OUTER] JOIN are a few popular join techniques.'

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6. Tell me the types of cursors in PL/SQL.

In SQL, a cursor is an area from which an application can retrieve data. The interviewer may test your knowledge of PL/SQL cursors in relation to writing data retrieval code. You can answer this question by defining and explaining the function of cursors.

Example: 'There are two types of cursors, namely the implicit cursor and the explicit cursor. For INSERT, UPDATE, DELETE and SELECT statements returning a single row, PL/SQL employs implicit cursors, while programmers develop explicit cursors for queries that return multiple rows.'

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7. Explain PL/SQL block.

Statements organised into units are PL/SQL blocks. When the interviewer asks this question, they want to test your basic knowledge of PL/SQL. While responding, mention the types of PL/SQL blocks and explain the concept using an example.

Example: 'PL/SQL blocks may contain variables, SQL statements, conditional statements, loops, constants and exceptions handling. PL/SQL blocks are of two types, which include anonymous blocks and named blocks. Anonymous blocks are the PL/SQL blocks without a header. These blocks do not form the body of a procedure, function or trigger. Named blocks are PL/SQL blocks which include labels or headers. These blocks may be subprograms such as functions, triggers packages or procedures.

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8. Describe COMMIT, ROLLBACK and SAVEPOINT.

The hiring manager may want to check if you are familiar with these terms. Sometimes the interviewer also asks such questions when you may require knowledge of such concepts for your role. Consider reading your job description thoroughly to get prepared for such questions.

Example: 'You can control the transaction using the COMMIT, ROLLBACK and SAVEPOINT command. The COMMIT command allows saving changes made to a database during the current transaction. At the conclusion of the current transaction, the ROLLBACK command executes and undoes all changes made since the start of the transaction. During the processing of a transaction, the SAVEPOINT command saves the current point with a unique name.'

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Tips To Prepare For The PL/SQL Interview

Following are some useful tips to help you better prepare for your PL/SQL interview:

  • Research about the company. Research the company, its work culture, product and services, goals and mission prior to the interview through its website, press releases and social profiles. This information may assist you in answering questions and convey to the hiring manager you took the time to conduct research.

  • Review the job description. Consider reviewing the job description prior to the interview and think about including your skills for the listed roles and responsibilities. Consider getting PL/SQL certificates if there is a specific requirement for the job.

  • Wear proper attire for the interview. It is important to wear proper and clean interview attire. You may do some research on the suitable interview attire for the PL/SQL interview to learn more about the available options.

  • Prepare yourself for the PL/SQL interview. Practise your answers to some mostly asked questions for the PL/SQL interview. You can consider asking fellow programmers for assistance in optimising your responses.

  • Understand the STAR method. STAR is an acronym for situation, task, action and outcome. Using the STAR method can help you answer more effectively in the interview.

  • Prepare questions to ask your interviewer. The hiring manager might ask you if you have questions about the role, company or the hiring procedure at the end of the interview. Consider preparing these questions in advance to help ensure you ask appropriate and thoughtful questions during your interview.

  • Follow up further to the interview. You may email the hiring manager, thanking them for their time and expressing your interest in the position after your interview. If they do not respond within a week, consider sending another email to enquire about the status of your application.

Please note that none of the companies, institutions or organisations mentioned in this article are associated with Indeed.

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