SQL interview questions are a critical piece of technical interviews and coding interviews. Most engineering roles, such as software engineer, data scientist, and data engineer, require SQL as a secondary skill. So, when you’re preparing for technical interviews, it is a good practice to prepare basic SQL questions. Some companies conduct separate SQL interview rounds for roles like data engineer and data scientist.
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To help you with your SQL interview preparation, we’ve gathered some frequently asked SQL interview questions. Here’s what we’ll discuss in this article:
SQL stands for Structured Query Language, a domain-specific language for managing data in the Database Management System (DBMS). Database Management System is a software that handles the creation, updation, and management of data.
SQL is one of the most desired skills in the market, as there is a massive usage of DBMS in every software. Every application or software you develop has some data associated with it and needs the DBMS principles to manage it.
There are basically five different types of commands in SQL:
In SQL Interviews, you can expect various questions to define terms, describe, or form a query. Here are some examples:
Some basic SQL interview questions are about defining a term in SQL. The interviewer may ask you to explain some technical concepts, explain the differences between two concepts, or explain how a concept works.
Following are some of the terms you should be familiar with to answer these SQL interview questions successfully:
In this type of SQL interview question, the interviewer will give a SQL query and ask some questions about it. Your answers to such questions convey your ability to read and interpret queries written by others.
These are the most common questions asked in SQL Interviews. Here, the interviewer will give the details of some tables and ask you to retrieve, update, or remove the data from those tables. The difficulty of these questions might vary based on the role you’re applying for. But, you can expect to get some questions on the following topics, statements, and clauses:
PL/SQL is an extension of SQL used in Oracle’s relational database. With PL/SQL, you can create powerful queries by combining the manipulation power of SQL and the processing power of procedural language.
Here are some popular interview questions on PL?SQL:
Read Facebook SQL Interview Questions to understand what kind of SQL interview questions you can expect at Facebook tech interviews.
You can also head over to Amazon SQL Interview Questions for some SQL questions asked in Amazon Interviews.
Follow these proven tips to answer and nail SQL interview questions:
1. Ask Questions
When the interviewer asks a question, take some time to understand the questions completely and ask clarifying questions if necessary. Know the datatypes of the columns present, if there are any primary keys etc.
2. Identify the Relevant Columns
You don’t require all the columns present in the table for your output. Identify the columns you need to work on, so you can concentrate on those.
3. Think About What Your Final Answer Should Look Like
While trying to solve the problem, keep the answer in your mind. Imagine what your final output should look like. This helps you to clear your mind and think about the logical ways to solve the problem.
4. Solve the Query One Step at a Time
Break down the problem into subparts and solve them one step at a time. If you have subqueries, start by solving the subquery first and then think about the main query. It helps you to concentrate on bits of the problem rather than the problem as a whole.
5. Include Comments
Include comments to explain what each step of your query performs. It helps you and the interviewer to understand the code and enables you to keep track of where you are.
6. Use Formatting
While you’re writing queries on a notebook, whiteboard, or sharing your screen, it’s essential to make the interviewer understand the query. Formatting the query helps the code look neat and concise and allows the interviewer to understand the code even before explaining it.
7. Talk Through the Process
It’s important to explain to the interviewer what you’re doing. It helps them understand how you approach a problem and give some tips if you’re stuck anywhere. So, make sure to explain what, why, and how of each step.
1. Is SQL hard to learn?
SQL is considered to be one of the easiest languages to learn. The syntax is similar to plain English, which makes it easy to read and understand.
2. Why do you use SQL?
SQL is used to communicate with Databases. It is used to access, read, update, and delete data from the Database.
3. Is SQL important for Interviews?
SQL skills are highly desirable in the market due to the massive use of DBMS in almost all the software being developed.
4. What are the basic SQL Commands?
SQL Commands are broadly classified into five categories. They are Data Definition Language, Data Manipulation Language, Data Query Language, Data Control Language, and Transaction Control Language, each having a separate functionality.
5. How do I prepare for an SQL interview?
To prepare for SQL interviews, you must first understand the types of questions asked during the interview. These include questions related to defining a term, questions about a given query, and questions that will require you to write a query. Practice questions from each category, and while practicing, be sure to follow the tips given in this article to structure your answers.
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