11 Thor Industries SQL Interview Questions (Updated 2024)
At Thor Industries, SQL is often for analyzing manufacturing data for efficient production, and forecasting market trends via historical sales data. For this reason Thor Industries frequently asks SQL query questions in interviews for Data Science, Data Engineering and Data Analytics jobs.
To help you ace the Thor Industries SQL interview, we've curated 11 Thor Industries SQL interview questions – scroll down to start solving them!
11 Thor Industries SQL Interview Questions
SQL Interview Question 1: Identify Power Users for Thor Industries
Given a database of Thor Industries, a company specializing in recreational vehicles, the goal is to identify users that purchase frequently, especially high-cost vehicles. For this exercise, the details of all transactions and the customer details are stored in two tables - and .
The table records each purchase made by a user. Each row in this table records a unique transaction, identified by , alongside the , , and .
The table contains relevant details about each user for the company, recording a unique alongside , , , .
Example Input:
| transaction_id | user_id | purchase_date | product_id | price |
|---|---|---|---|---|
| 4001 | 501 | 2022-08-25 10:15:00 | 10501 | 125000 |
| 4002 | 502 | 2022-06-15 15:50:00 | 10502 | 145000 |
| 4003 | 501 | 2022-06-05 12:12:00 | 10503 | 160000 |
| 4004 | 503 | 2022-07-03 13:13:00 | 10504 | 125000 |
| 4005 | 504 | 2022-08-01 11:25:00 | 10501 | 130000 |
Example Input:
| user_id | first_name | last_name | registration_date | |
|---|---|---|---|---|
| 501 | John | Doe | john.doe@email.com | 2022-01-01 |
| 502 | Jane | Smith | jane.smith@email.com | 2022-02-10 |
| 503 | Harry | Potter | harry.potter@email.com | 2022-04-12 |
| 504 | Hermione | Granger | hermione.granger@email.com | 2022-03-14 |
Your task is to write a query to identify those users who have made the maximum number of purchases above a certain price point (for example, $100,000).
Answer:
Your SQL query would look something like this:
This query first joins and tables on . Then it filters for only those transactions where is greater than $100,000. It then groups the result by , , and . Finally, it counts the number of transactions per user (as ) and sorts the users by this count in descending order, giving us the "power users".
To solve a related customer analytics question on DataLemur's free interactive SQL code editor, try this Microsoft Azure Cloud SQL Interview Question:
Check out the Thor Industries career page to learn what expectations they have for their roles!
SQL Question 2: Employees Earning More Than Their Boss
Imagine there was a table of Thor Industries employee salary data. Write a SQL query to find all employees who earn more than their direct manager.
Thor Industries Example Input:
| employee_id | name | salary | department_id | manager_id |
|---|---|---|---|---|
| 1 | Emma Thompson | 3800 | 1 | |
| 2 | Daniel Rodriguez | 2230 | 1 | 10 |
| 3 | Olivia Smith | 8000 | 1 | 8 |
| 4 | Noah Johnson | 6800 | 2 | 8 |
| 5 | Sophia Martinez | 1750 | 1 | 10 |
| 8 | William Davis | 7000 | 2 | NULL |
| 10 | James Anderson | 4000 | 1 | NULL |
Example Output:
| employee_id | employee_name |
|---|---|
| 3 | Olivia Smith |
This is the output because Olivia Smith earns $8,000, surpassing her manager, William Davis who earns 7,800.
Solve this interview question directly within the browser on DataLemur:
Answer:
First, we perform a SELF-JOIN where we treat the first table () as the managers' table and the second table () as the employees' table. Then we use a clause to filter the results, ensuring we only get employees whose salaries are higher than their manager's salary.
If the code above is hard to understand, you can find a step-by-step solution here: Well Paid Employees.
SQL Question 3: Can you explain what / SQL commands do?
The / operator is used to remove to return all rows from the first SELECT statement that are not returned by the second SELECT statement.
Note that is available in PostgreSQL and SQL Server, while MINUS is available in MySQL and Oracle (but don't worry about knowing which DBMS supports which exact commands since Thor Industries interviewers aren't trying to trip you up on memorizing SQL syntax).
For a tangible example of in PostgreSQL, suppose you were doing an HR Analytics project for Thor Industries, and had access to Thor Industries's contractors and employees data. Assume that some employees were previously contractors, and vice versa, and thus would show up in both tables.
You could use operator to find all contractors who never were a employee using this query:
SQL Question 4: Calculate Monthly Sales for Each Product
Given a database table which contains sales transactions data for Thor Industries, write a SQL query to calculate the total sales and the average sales for each product on a monthly basis.
Example Input:
| sales_id | product_id | sales_date | sales_amount |
|---|---|---|---|
| 1 | 550 | 01/10/2022 | 3000 |
| 2 | 450 | 01/15/2022 | 2000 |
| 3 | 550 | 01/18/2022 | 3500 |
| 4 | 450 | 02/05/2022 | 1500 |
| 5 | 300 | 02/18/2022 | 1200 |
| 6 | 300 | 02/22/2022 | 3600 |
| 7 | 550 | 03/10/2022 | 4000 |
| 8 | 450 | 03/15/2022 | 2500 |
Example Output:
| month | product_id | total_sales | average_sales |
|---|---|---|---|
| 1 | 550 | 6500 | 3250 |
| 1 | 450 | 2000 | 2000 |
| 2 | 450 | 1500 | 1500 |
| 2 | 300 | 4800 | 2400 |
| 3 | 550 | 4000 | 4000 |
| 3 | 450 | 2500 | 2500 |
Answer:
This SQL query uses PostgreSQL's EXTRACT function to get the month from the column. It then groups the sales by and to calculate the summation () and average () of sales amount for each product per month. The query then orders the result by and .
To solve a related window function SQL problem on DataLemur's free interactive SQL code editor, solve this Google SQL Interview Question:
SQL Question 5: What are database views used for?
A database view is a virtual table that is created based on the results of a SELECT statement, and provides you a customized, read-only version of your data that you can query just like a regular table.
Views in SQL can help you enforce data security requirements by hiding sensitive data from certain users, and can improve performance for some queries by pre-computing the results for an intermediate step and storing them in a view (which can be faster than executing the intermediate query each time). However, their read-only nature means that on any underlying update, the view has to be re-computed.
SQL Question 6: RV Inventory and Sales
Thor Industries is a global leader in designing, manufacturing and selling RVs (recreational vehicles). Your task is to design a database to track their RV inventory and sales.
You have to consider the following:
- An RV belongs to a specific model.
- A model belongs to a brand.
- Each RV has a unique serial number.
- Each RV model has a name, a brand and a base price.
- The RV sale transaction includes the sales price, sales date, buyer's name, and serial number of the RV sold.
Based on the above scenario, you may likely have four tables, namely 'brands', 'models', 'rvs' and 'sales'. Here are some sample data:
Example Input:
| brand_id | brand_name |
|---|---|
| 1 | Airstream |
| 2 | Jayco |
| 3 | Heartland RV |
Example Input:
| model_id | model_name | brand_id | base_price |
|---|---|---|---|
| 1 | Flying Cloud | 1 | 73900 |
| 2 | Eagle | 2 | 44900 |
| 3 | Milestone | 3 | 56900 |
Example Input:
| rv_id | serial_no | model_id |
|---|---|---|
| 1 | THOR00001 | 1 |
| 2 | THOR00002 | 2 |
| 3 | THOR00003 | 3 |
Example Input:
| sales_id | sales_price | sales_date | buyer_name | rv_id |
|---|---|---|---|---|
| 1 | 80000 | 06/08/2022 15:24:00 | John Doe | 1 |
| 2 | 46000 | 07/18/2022 14:30:00 | Jane Doe | 2 |
| 3 | 58000 | 07/26/2022 10:10:00 | Joe Doe | 3 |
Answer:
To get the total sales, average sale price and number of RVs sold by brand for a given period, consider the following PostgreSQL query:
This query first joins all the necessary tables based on the relationships between them. This allows to access the brand name for a sold RV. It then restricts the rows based on the sales date and groups the results by brand name. Finally, it computes the count, average and sum aggregates on the appropriate columns.
SQL Question 7: Could you clarify the difference between a left and a right join?
A join in SQL combines rows from two or more tables based on a shared column or set of columns. To demonstrate the difference between a and , say you had a table of Thor Industries orders and Thor Industries customers.
LEFT JOIN: A retrieves all rows from the left table (in this case, the Orders table) and any matching rows from the right table (the Customers table). If there is no match in the right table, NULL values will be returned for the right table's columns.
RIGHT JOIN: A retrieves all rows from the right table (in this case, the Customers table) and any matching rows from the left table (the Orders table). If there is no match in the left table, NULL values will be returned for the left table's columns.
SQL Question 8: Filter Customers based on Membership Status and Purchase History
Thor Industries wants to do a promotional campaign for their RV products (Recreational Vehicles). They have asked to filter down the customer records for those customers who have membership status as 'Active', have bought at least one RV in the past and their most recent purchase was made within the last 6 months. Also, they want the list to be ordered by the most recent purchase date.
Example Input:
| customer_id | first_name | last_name | membership_status |
|---|---|---|---|
| 001 | John | Doe | Active |
| 002 | Alice | Smith | Inactive |
| 003 | Steve | Johnson | Active |
| 004 | Emma | Watson | Active |
Example Input:
| purchase_id | customer_id | purchase_date | product |
|---|---|---|---|
| 1001 | 001 | 2022-05-24 | RV |
| 1002 | 001 | 2021-11-15 | Accessory |
| 1003 | 002 | 2022-06-01 | RV |
| 1004 | 003 | 2022-01-24 | RV |
| 1005 | 004 | 2022-06-02 | Trailer |
Example Output:
| customer_id | first_name | last_name | most_recent_purchase_date |
|---|---|---|---|
| 001 | John | Doe | 2022-05-24 |
| 004 | Emma | Watson | 2022-06-02 |
Answer:
This SQL query first joins the and tables on the field. The clause is then applied to filter for customers who have 'Active' membership status, have bought an 'RV' product, and the purchase date is within the last 6 months. The clause is used to aggregate records by customer and the function is used to find the most recent purchase date for each customer. The result is then ordered in descending order by the most recent purchase date.
SQL Question 9: Analyzing Click-Through Rates for Thor Industries
Thor Industries, a leading recreational vehicle manufacturer, wants to evaluate the effectiveness of their new digital marketing campaign. They're specifically interested in the click-through rate of the advertisement they've placed on various platforms leading visitors to product pages on their website, and then how often these visits translate into a product being added to the shopping cart.
The data they've collected is stored in two tables: and .
Example Input:
| click_id | user_id | ad_platform | timestamp | product_id |
|---|---|---|---|---|
| 1056 | 5789 | 'Facebook' | '2022-07-20 14:32:21' | A101 |
| 2248 | 7624 | 'Google' | '2022-07-22 08:15:34' | A102 |
| 3789 | 1205 | 'Instagram' | '2022-07-22 19:20:43' | A103 |
| 4562 | 2981 | 'Facebook' | '2022-07-23 07:54:56' | A101 |
| 5869 | 5690 | 'Google' | '2022-07-24 22:34:12' | A102 |
Example Input:
| add_id | user_id | timestamp | product_id |
|---|---|---|---|
| 1023 | 5789 | '2022-07-20 14:35:18' | A101 |
| 2479 | 7624 | '2022-07-23 09:50:46' | A102 |
| 3912 | 2981 | '2022-07-23 09:00:43' | A101 |
Answer:
This query first generates two separate subqueries: and . The subquery calculates the number of clicks per ad platform for each product. The subquery makes a join between the and tables on the and fields, then calculates the number of add-to-cart actions that occur after the click took place. Finally, we join and on and , and calculate the click-through conversion rate as the ratio of total adds to total clicks, expressed as a percentage.
To practice a similar problem on DataLemur's free online SQL coding environment, attempt this Meta SQL interview question:
SQL Question 10: Database transactions are supposed to be atomic, consistent, isolated, & durable. What does each term mean?
A DBMS (database management system), in order to ensure transactions are relaible and don't ruin the integrity of the data, tries to mantain the following ACID properties: Atomicity, Consistency, Isolation, and Durability.
To make this concept more concrete, here is what each of the ACID properties would mean in the context of banking transactions:
- Atomicity: a transaction is either completed fully, or not complete at all. For example, if a customer is transferring money from one account to another, the transaction should either transfer the full amount or none at all.
- Consistency: a transaction will only be completed if it follows all database constraints and checks. For example, if a customer is withdrawing money from an account, the transaction should only be completed if the account has sufficient funds available, otherwise the transaction is rejected
- Isolation: ensures that concurrent transactions are isolated from each other, so that the changes made by one transaction cannot be seen by another transaction. This isolation prevents race conditions, like two customers trying to withdraw money from the same account at the same time.
- Durability: ensures that once a transaction has been committed and completed, the changes are permanent. A reset / shutdown of the database shouldn't erase someone's savings accounts!
SQL Question 11: Average Sales of Each Caravan Model per Month
Thor Industries is a manufacturer of recreational vehicles. As an SQL analyst at the company, your task is to find out the average sales each month, broken down by caravan model. This will help in understanding which models are more popular in different months of the year.
Example Input:
| sale_id | date_sold | caravan_model_id | price |
|---|---|---|---|
| 1264 | 01/05/2022 | 101 | 25000 |
| 8745 | 01/25/2022 | 102 | 30000 |
| 5438 | 01/30/2022 | 101 | 27000 |
| 2684 | 02/15/2022 | 101 | 26000 |
| 3786 | 02/20/2022 | 102 | 29000 |
Example Output:
| month | caravan_model | average_price |
|---|---|---|
| 1 | 101 | 26000.00 |
| 1 | 102 | 30000.00 |
| 2 | 101 | 26000.00 |
| 2 | 102 | 29000.00 |
Answer:
This PostgreSQL query extracts the month from the column and groups the sales by both month and . It then calculates the average in each group. The clause ensures that the results are sorted first by month and then by caravan model.
Thor Industries SQL Interview Tips
The best way to prepare for a Thor Industries SQL interview is to practice, practice, practice.
Besides solving the above Thor Industries SQL interview questions, you should also solve the 200+ DataLemur SQL Interview Questions which come from companies like Facebook, Google, and VC-backed startups.
Each DataLemur SQL question has hints to guide you, detailed solutions and crucially, there's an online SQL code editor so you can right online code up your SQL query answer and have it executed.
To prep for the Thor Industries SQL interview it is also helpful to solve SQL problems from other automotive companies like:
However, if your SQL skills are weak, don't worry about jumping right into solving questions – refresh your SQL knowledge with this DataLemur SQL Tutorial.
This tutorial covers topics including CASE/WHEN statements and finding NULLs – both of which come up frequently during Thor Industries interviews.
Thor Industries Data Science Interview Tips
What Do Thor Industries Data Science Interviews Cover?
In addition to SQL interview questions, the other topics covered in the Thor Industries Data Science Interview are:
- AB Testing Questions
- Python Pandas or R Coding Questions
- Analytics and Product-Metrics Questions
- ML Interview Questions
- Behavioral Interview Questions
How To Prepare for Thor Industries Data Science Interviews?
I'm sorta biased, but I think the best way to study for Thor Industries Data Science interviews is to read my book Ace the Data Science Interview.
The book has 201 interview questions taken from Google, Microsoft & tech startups. It also has a refresher covering Product Analytics, SQL & ML. And finally it's helped a TON of people, which is why it's got over 1000+ 5-star reviews on Amazon.