Top 10 SQL Scenario Based Interview Questions and Answers

SQL Scenario based interview questions are a common type of question that may be asked during an SQL interview. These types of questions present a hypothetical situation or problem and ask the interviewee to solve it using SQL skills and knowledge. Scenario-based questions are often used to evaluate an applicant’s ability to think critically and problem-solve in a real-world setting. In this article, we will provide examples of scenario-based questions that may be asked in an SQL interview and offer tips for approaching and answering them effectively.

SQL Scenario Based Interview Questions

1. “You are a data analyst at a company and have been asked to identify the top 5 products by total sales for the last quarter. The data is stored in a table with the following columns: product_id, product_name, quantity, price, and order_date. Write a query to generate the report.”
2. “You are a data scientist at a company and have been asked to analyze website traffic data. The data is stored in a table with the following columns: date, page_views, unique_visitors, and bounce_rate. Write a query to calculate the average bounce rate for the last 30 days.”
3. “You are a database administrator at a company and have been asked to design a database backup and recovery plan. The database stores critical business data and needs to be backed up regularly to ensure data integrity and availability. How would you design the backup and recovery plan and why?”
4. “You are a data engineer at a company and have been asked to design a database to store information about a ride-sharing service. The database will need to store information about drivers, riders, rides, and payments. How would you design the database schema and why?”
5. “You are a data analyst at a company and have been asked to identify the top 5 customers by total purchases in the last year. The data is stored in a table with the following columns: customer_id, order_id, order_date, product, quantity, and price. Write a query to generate the report.”
   “You are a data scientist at a company and have been asked to analyze employee attendance data. The data is stored in a table with the following columns: employee_id, date, attendance_status (either “present” or “absent”). Write a query to calculate the percentage of days each employee was absent in the last 90 days.”
6. “You are a database administrator at a company and have been asked to optimize a slow-running query that retrieves data from a large table. The query currently takes several minutes to run and the table has millions of rows. How would you go about optimizing the query and why?”
7. “You are a data analyst at a company and have been asked to create a report that shows the total sales by product category for the last year. The data is stored in a table with the following columns: order_id, order_date, product, quantity, price, and category. Write a query to generate the report.”
8. “You are a data engineer at a company and have been asked to design a database to store information about a music streaming service. The database will need to store information about users, tracks, albums, and artists. How would you design the database schema and why?”

SQL Scenario Based Interview Questions on Joins

1. “You are a data analyst at a company and have been asked to generate a report showing the total sales by salesperson for the last quarter. The data is stored in two tables: sales and salespeople. The sales table has the following columns: order_id, order_date, product, quantity, price, and salesperson_id. The salespeople table has the following columns: salesperson_id, first_name, and last_name. Write a query to generate the report using an inner join.”
2. “You are a data engineer at a company and have been asked to design a database to store information about a music streaming service. The database will need to store information about users, tracks, albums, and artists. The tracks table has the following columns: track_id, title, and album_id. The albums table has the following columns: album_id, title, and artist_id. The artist’s table has the following columns: artist_id, first_name, and last_name. Write a query to retrieve the title of each track and the name of the artist who performed it using a left outer join.”
3. “You are a data scientist at a company and have been asked to analyze website traffic data. The data is stored in two tables: pageviews and visitors. The pageviews table has the following columns: date, page_id, and page_views. The visitors table has the following columns: date, visitor_id, and unique_visitors. Write a query to calculate the total number of pageviews and unique visitors for each date using a full outer join.”
4. “You are a database administrator at a company and have been asked to optimize a slow-running query that retrieves data from two large tables. The first table, orders, has the following columns: order_id, order_date, and customer_id. The second table, customers, has the following columns: customer_id, first_name, and last_name. The query currently takes several minutes to run and the tables have millions of rows. Write a query to retrieve the order_id, order_date, and customer name for each order using a right outer join and appropriate indexing to optimize performance.”

SQL Questions and How to Answer Them

Here are some examples of scenario-based questions that might be asked in an SQL interview, along with suggestions for how to approach answering them:

1. “You are a data analyst at a company and have been asked to analyze customer purchase data. The data is stored in a table with the following columns: customer_id, purchase_date, product, quantity, and price. Write a query to calculate the total amount spent by each customer in the last 30 days.”
   To answer this question, you could start by breaking down the scenario and asking clarifying questions if necessary. Then, you could identify the specific task or problem that needs to be solved: calculating the total amount spent by each customer in the last 30 days. Next, you could think through the steps needed to solve the task or problem. In this case, you might need to filter the data to only include purchases made in the last 30 days, group the data by customer_id, and calculate the total amount spent for each customer using the quantity and price columns. You could also consider edge cases and potential issues that may arise, such as null values in the quantity or price columns. Finally, you can communicate your thought process and solution clearly by explaining the steps you took and showing the final query.
2. “You are a data engineer at a company and have been asked to design a database schema for storing customer information. The customer information includes their name, email, address, and phone number. How would you design the schema and why?”
   To answer this question, you could start by breaking down the scenario and asking clarifying questions if necessary. Then, you could identify the specific task or problem that needs to be solved: designing a database schema for storing customer information. Next, you could think through the steps needed to solve the task or problem. In this case, you might need to consider the data types and attributes of each piece of customer information and how they should be organized in the schema. You could also consider any additional information that might be useful to store, such as the customer’s account balance or membership status. As you design the schema, you should also consider any constraints or relationships that may exist between different pieces of data. Finally, you can communicate your thought process and solution clearly by explaining the decisions you made and showing the final schema design.

Tips for answering scenario-based questions

Here are some tips for approaching and answering scenario-based questions effectively:

1. Break down the scenario and ask clarifying questions if necessary. It can be helpful to understand the context and specific details of the scenario before diving into the problem-solving process.
2. Identify the specific task or problem that needs to be solved. Make sure you understand the question being asked and the desired outcome before proceeding.
3. Think through the steps needed to solve the task or problem. Consider what information and resources you have available and how you can use them to arrive at a solution.
4. Consider edge cases and potential issues that may arise. Anticipating and addressing potential roadblocks can help ensure that your solution is robust and effective.
5. Communicate your thought process and solution clearly. Explain the steps you took and the reasoning behind your decisions. Use clear and concise language and provide examples or demonstrations of your solution if appropriate.

Conclusion

In conclusion, SQL scenario based questions is a common type of question that may be asked in an SQL interview. These types of questions present a hypothetical situation or problem and ask the interviewee to solve it using SQL skills and knowledge. To effectively answer scenario-based questions, it can be helpful to break down the scenario and ask clarifying questions, identify the specific task or problem that needs to be solved, think through the steps needed to solve the task or problem, consider edge cases and potential issues that may arise, and communicate your thought process and solution clearly. By practicing answering scenario-based questions, you can become more comfortable and confident in technical interviews.