12 Questions to Ask at a PL/SQL Interview in 2022 (With Answers and Tips)
Developers can use PL/SQL, a procedural language, to query databases. The technology goes beyond SQL and can give more ways to work with data. If you study the top PL/SQL interview questions, you’ll be better able to answer questions during your interview.
In this article, we explain what a PL/SQL developer does, give you 12 sample PL/SQL interview questions and answers, and give you tips on how to ace your interview.
What does a PL/SQL developer do?
PL/SQL developers design, create, debug and optimize PL/SQL program units. Depending on what the company needs, the developer may also take care of the network interfaces of PL/SQL programs. A PL/SQL package is a group of related database data that you can look up by its name. Some skills PL/SQL programmers may have include:
- Knowing about the Microsoft SQL server
- Taking care of and running a database
- Joins in SQL and other SQL skills
- Analysis of technical SQL data
- Problem-solving and making choices
- Think carefully
12 PL/SQL developer interview questions
Here are 12 examples of questions and answers for a PL/SQL developer interview:
1.What is Oracle’s PL/SQL language?
This question may be asked by the interviewer to see if you know how the PL/SQL programming language came to be. This question can also be used to see if you can describe how a technical tool works. To answer, you can explain what PL/SQL is and what it can do.
Example: “PL/SQL is a procedural language, which means that programmers can use it to tell how a task should be done by listing a series of steps. Conditional statements like “if else” and loops are used in these steps. PL/SQL is an add-on to SQL, and SQL statements can be used in its syntax. By combining SQL with procedural instructions, the tool also makes SQL more useful. For faster query processing, programs send statements from the language to the database engine.”
2. What are some things that PL/SQL can do?
If you know how a language works, you can use it for programming tasks that are right for it. Your interviewer might ask you this question to find out how well you know how to use PL/SQL to solve different database problems. You can answer by talking about the basic things the technology can do.
Example: “Because PL/SQL is procedural, programmers can use it to tell database programs how to make decisions, branch, and loop. You can also use one PL/SQL command to run multiple queries as a single block. PL/SQL code can be reused by applications if it is stored in databases as functions, types, and triggers. With this feature, multiple applications can use the same PL/SQL subprograms and share them.”
3.What is the difference between PL/SQL and Oracle SQL?
Your interviewer may ask you this to see if you know which language to use for a certain task. Depending on what they can do, database administrators can choose from different query tools to solve a certain programming problem. You can answer by giving specific examples of how SQL and PL/SQL are different.
Example: “While SQL is a query language, PL/SQL is a procedural language. SQL can run one command, but PL/SQL can run a block of code statements. You can use SQL to write queries that define and change databases. When writing program blocks, procedures, functions, triggers, and packages, PL/SQL may be more useful for programmers. SQL can be a useful tool for doing set-based operations and managing data. Because PL/SQL is code that runs on the server, it can do more complex tasks than SQL. With this attribute, you can put SQL statements inside of PL/SQL.”
4. What kinds of data can be used in PL/SQL?
Knowing PL/SQL data types, what they can do, and what they can’t do can help programmers make better database queries. This question could be used by the hiring manager to see how well you can handle different types of data in PL/SQL. You can answer by giving a list of PL/SQL data types and telling what each one is used for.
Example: “Scalar, composite, reference, and large object are the four types of data that come with PL/SQL. Programmers can also make their own subtypes of data. The data types and subtypes determine how database variables are stored, as well as their constraints, valid value ranges, and operations.
Scalar is a type of data that only has one value and no internal parts. It breaks up into character data, numeric data, boolean data, and daytime data. Composite types are made up of separate pieces of data that you can change and process separately. Reference types can be used to store reference values that hold the addresses of other program variables. The large object data type’s locators tell the system where to store big things like text, videos, and images.”
5. What is a package in PL/SQL?
In PL/SQL, packages are schema objects that group data that goes together. Your interviewer might use this question to see how well you know how to use PL/SQL packages in big database systems. You can explain what PL/SQL packages are and what they contain in your answer.
Example: “A PL/SQL package is an object in the database schema. The object contains groupings of related data types and subprograms. There are cursors, exception names, and type statements among these data types. The two parts of a package are the specification and the body. With package specifications, you can set up public procedures, functions, variables, objects, cursors, subprograms, constants, and exceptions.
All of these declared elements are public elements because a program can use them from outside the package. The package body has coded definitions of all the subprograms and elements that have been declared, as well as some that have not been declared and are private.”
6.What are some of the good things about PL/SQL packages?
There may be ways to use package elements in programming that aren’t in the SQL language. Your interviewer may ask you this question to see if you know what PL/SQL packages are and what they do in application development. You can answer by giving examples of how the packages improve the way the computer works and how well it works.
Example: “With a PL/SQL package, you can store functions and procedures that work together in a single unit. Programs run faster because the package lets the memory load several objects at once. When all the code blocks run at the same time, the system cuts down on traffic, which speeds up the processing.
Developers can make object-oriented interfaces with a PL/SQL package by referring to the hidden code in the package. They can use and control package modules and data structures with the help of these interfaces. When you change one module in a PL/SQL package, you can change another because the package objects are used by all application objects as global data.”
7. What are PL/SQL joins?
Large datasets may be stored in many database tables by people in charge of the database. The hiring manager can ask you this to find out if you know how to get data from more than one table. You can answer by explaining what joins are and how you use them.
Example: “A join is a technique to retrieve data from over one table and combine it into a single result set. You can join tables in two ways: with syntax that is not ANSI or with syntax that is ANSI. Developers might like the ANSI join syntax because it is easier to use, works with more database engines, and can do more. [INNER] JOIN, LEFT [OUTER] JOIN, and RIGHT [OUTER] JOIN are all common ways to join data. In the code, you may also see FULL [OUTER] JOIN, CROSS JOIN, NATURAL JOIN, and [INNER] JOIN.”
8. What are cursors in PL/SQL?
In SQL, a cursor is a private area where data can be pulled by an application. The interviewer might ask you about how you use PL/SQL cursors when writing code to get data. You can answer by explaining what cursors are and how they work.
Example: “A cursor is a way to get to a certain place in memory. Cursors are used by the PL/SQL program to choose and get multiple rows of data from the database. There are two kinds of cursors in PL/SQL. They are called explicit and implicit. If you are writing code for queries that return many rows, you can declare and name an explicit cursor. When any SQL statement is run, PL/SQL automatically creates implicit cursors without the need for a definition.”
9. Explain how PL/SQL is put together.
During compilation, SQL statements are turned into machine code. The hiring manager might use this question to see how well you know how to use compilation processes to improve how well an application works. In your answer, you can talk about the steps you need to take to compile PL/SQL.
Example: “Native compilation is the process of turning PL/SQL modules into native code that can be found in shared libraries. The data dictionary is where you can find these libraries. The module turns procedures in a program into C code. Then, a C compiler puts them all together and links them to the system process on the fly. You can set a session parameter before writing the code if you don’t have a C compiler. Programmers can also make and improve byte code with MCode. The PL/SQL runtime engine reads MCode from the database dictionary and runs it.”
10.What’s the difference between a simple view and a complicated one?
A database view is a smaller section of a large database. An interviewer might ask you this question to see how well you understand how PL/SQL views work. You can answer by saying how the two points of view are different.
Example: “The way that simple view and complex view get their data is different in PL/SQL. Simple view gets data from a single table, while complex view can get data from more than one table. In simple view, you can’t use functions or data groups, but you can in complex view. In simple view, you can make changes to the data, which may not be possible in complex view.”
11. What are PL/SQL triggers?
This question can test how well you know how to find and fix PL/SQL database errors. Exceptions can happen when the database isn’t set up right or when there are mistakes in the code. You can answer by explaining what exception handling is and how it works.
Example: “An error in the code can cause a program to stop running right away. This is called an exception. In PL/SQL, there are three types of exceptions: those that are predefined, those that are not defined, and those that are defined by the user. The PL/SQL program has set up the predefined type to handle common errors, while the undefined type takes care of errors that might be new to the program. Programmers can make user-defined exceptions to handle custom error situations, like when someone tries to get in without permission.”
12. What’s good about using triggers?
Your interviewer wants to know if you know how to use triggers to make coding easier. Try to explain in your answer how triggers can make using the database management system easier.
Example: “Triggers make it easier to change the way a database is managed. For example, a trigger will create virtual column values on its own if you want them. Also, triggers let you record events and keep track of how a table is used. You can also use referential integrity, stop invalid transactions, and let subscribing applications know about database and user events.”
Tips for a PL/SQL developer interview
Here are some things to think about as you get ready for your PL/SQL interview:
- Find out about the company’s culture and goals by doing some research. You can look around the company’s website, check their social media accounts, and read their press releases.
- Check to see if you have the technical skills needed for the job. If you don’t have the right skills for the job, you might want to take PL/SQL certifications.
- Find out how much PL/SQL developers make. If you know how much PL/SQL developers make in your area, you can give your interviewer a rough idea when they ask what you want to make.
- Make a list of PL/SQL interview questions and short answers to those questions. You can go to different forums for database programming and ask other coders to help you improve the way you answer questions.
- Practice answering questions about PL/SQL. You can improve your communication skills by answering questions out loud or asking a friend to do a mock interview with you.