8 Applied SQL Interview Questions (Updated 2024)
Applied employees write SQL queries to analyze inventory data, helping them find the best ways to manage stock and reduce waste. They also use SQL to explore customer databases, discovering helpful insights about buying trends to guide product and marketing decisions, this is why Applied includes SQL coding questions in interviews for Data Analyst, Data Science, and BI jobs.
So, to help you prep, we've collected 8 Applied Industrial Technologies SQL interview questions – able to answer them all?
8 Applied Industrial Technologies SQL Interview Questions
SQL Question 1: Analyze Monthly Product Ratings
For a company like Applied, it's important to track and analyze product feedback from users over time to make improvements. With this in mind, can you write a SQL query to calculate the average star rating for each product on a monthly basis?
Let's assume we have a table where each row represents one product review submitted by a user, with a unique review ID, the ID of the user who made the review, the date the review was submitted, the product ID of the product being reviewed, and the number of stars given for the review.
Here's an example of what the table might look like:
Example Input:
| review_id | user_id | submit_date | product_id | stars |
|---|---|---|---|---|
| 6171 | 123 | 2022-06-08 | 50001 | 4 |
| 7802 | 265 | 2022-06-10 | 69852 | 4 |
| 5293 | 362 | 2022-06-18 | 50001 | 3 |
| 6352 | 192 | 2022-07-26 | 69852 | 3 |
| 4517 | 981 | 2022-07-05 | 69852 | 2 |
Your result should return the month, the product ID, and the average star rating for each product per month. Make sure your result is ordered chronologically.
Example Output:
| month | product_id | avg_stars |
|---|---|---|
| 6 | 50001 | 3.50 |
| 6 | 69852 | 4.00 |
| 7 | 69852 | 2.50 |
Answer:
The query uses the function to get the month from the column. It then groups all reviews by month and product ID, and calculates the average star rating for each group using the function. The clause is used to order the results chronologically.
For more window function practice, try this Uber SQL problem within DataLemur's online SQL code editor:
Explore the latest updates from Applied Industrial Technologies and discover how they are driving innovation in the industrial sector! Keeping an eye on their pressroom can help you understand the company's commitment to excellence and how they are adapting to meet industry demands.
SQL Question 2: 2nd Largest Salary
Suppose there was a table of Applied employee salary data. Write a SQL query to find the 2nd highest salary at the company.
Applied Example Input:
| employee_id | salary |
|---|---|
| 1 | 2500 |
| 2 | 800 |
| 3 | 1000 |
| 4 | 1200 |
Example Output:
| second_highest_salary |
|---|
| 1200 |
Test your SQL query for this interview question interactively on DataLemur:
Answer:
You can find a detailed solution with hints here: 2nd Highest Salary.
SQL Question 3: How is the constraint used in a database?
A is a field in a table that references the of another table. It creates a link between the two tables and ensures that the data in the field is valid.
Say for example you had sales analytics data from Applied's CRM (customer-relationship management) tool.
In this example, the table has a foreign key field called that references the" field in the table (the primary key). This helps to link the data about each opportunity to the corresponding account information in the accounts table.
This makes sure the insertion of rows in the table that do not have corresponding entries in the table. It also helps to enforce the relationship between the two tables and ensures that data is not deleted from the table if there are still references to it in the table.
SQL Question 4: Database Design for Job Applicants' Management
Applied is a company that handles job applications for several other companies. They need a way to track every job opening, the applicant, and their progress through the application process. The following information should be captured:
- Job: Job id, company id, position, job status (open or closed)
- Company: Company id, company name, industry
- Applicant: Applicant id, name, contact details
- Application: Job id, applicant id, application date, status (applied, in-review, rejected, hired)
Design a database for this scenario, identifying the tables, fields and the relationships between these tables.
Sample Data
Sample Input:
| job_id | company_id | position | status |
|---|---|---|---|
| 1 | 101 | "Software Engineer" | "Open" |
| 2 | 102 | "Data Analyst" | "Closed" |
| 3 | 103 | "Product Manager" | "Open" |
Sample Input:
| company_id | name | industry |
|---|---|---|
| 101 | "Google" | "Tech" |
| 102 | "Deloitte" | "Consulting" |
| 103 | "Apple" | "Tech" |
Sample Input:
| applicant_id | name | contact_details |
|---|---|---|
| 201 | "John Doe" | "johndoe@example.com" |
| 202 | "Jane Smith" | "janesmith@example.com" |
| 203 | "Emma Jones" | "emmajones@example.com" |
Sample Input:
| job_id | applicant_id | app_date | status |
|---|---|---|---|
| 1 | 201 | "20/10/2022" | "Applied" |
| 2 | 202 | "15/09/2022" | "Rejected" |
| 3 | 203 | "22/10/2022" | "In-Review" |
Answer:
Here is a sample PostgreSQL query to fetch the current status of all applicants:
This query makes use of JOIN operator to combine rows from two or more tables, based on a related column between them. The result would provide a clear view of the application progress for each applicant, with their name, job position applied to, the company name and the current status of their application. This information could be particularly helpful for HR managers in tracking the recruitment process.
SQL Question 5: How can you select records without duplicates from a table?
"The clause in SQL allows you to select records that are unique, eliminating duplicates.
For a tangible example, say you had a table of Applied employees:
| first_name | job_title |
|---|---|
| Akash | Data Analyst |
| Brittany | Data Scientist |
| Carlos | Data Engineer |
| Diego | Data Engineer |
| Eva | Data Analyst |
If you were doing an HR Analytics project and you wanted to get all the unique job titles that currently worked at the company, you would write the following SQL query:
The output would give you 3 distinct job titles at Applied:
| job_title |
|---|
| Data Analyst |
| Data Scientist |
| Data Engineer |
SQL Question 6: Filter the Customer Records
You're working for an ecommerce company that wants to improve its customer targeting strategy. The marketing team asked you to identify customers who have made at least 3 purchases in the last 6 months and have spent more than $300 overall. Can you write a SQL query to find these customers?
Example Input:
| order_id | customer_id | order_date | total_price |
|---|---|---|---|
| 75632 | 111 | 01/15/2022 | 150.00 |
| 75633 | 222 | 03/10/2022 | 50.00 |
| 75634 | 111 | 03/20/2022 | 60.00 |
| 75635 | 333 | 03/21/2022 | 100.00 |
| 75636 | 111 | 05/15/2022 | 100.00 |
| 75637 | 222 | 06/10/2022 | 200.00 |
Answer:
This query will return customers who match the given criteria. It first filters the orders within the last 6 months. It then groups the records by and counts the number of orders per customer and calculates the total spent. Finally, it applies a clause to filter the groups according to the condition given by the marketing team.
SQL Question 7: Can you list the various types of joins in SQL, and describe their purposes?
Using a join in SQL, you can retrieve data from multiple tables and merge the results into a single table.
In SQL, there are four distinct types of JOINs. To demonstrate each kind, Imagine you had two database tables: an table that contains data on Google Ads keywords and their bid amounts, and a table with information on product sales and the Google Ads keywords that drove those sales.
-
: An retrieves rows from both tables where there is a match in the shared key or keys. For example, an between the table and the table could be performed using the keyword column as the shared key. This would retrieve only the rows where the keyword in the table matches the in the table.
-
: A retrieves all rows from the left table (in this case, the table) and any matching rows from the right table (the table). If there is no match in the right table, values will be returned for the right table's columns.
-
: A retrieves all rows from the right table (in this case, the table) and any matching rows from the left table (the table). If there is no match in the left table, values will be returned for the left table's columns.
-
: A retrieves all rows from both tables, regardless of whether there is a match in the shared key or keys. If there is no match, values will be returned for the columns of the non-matching table.
SQL Question 8: Find the Average Salary per Department
Assume Applied is a company that has various departments and employees. Each employee has a salary, and belongs to a department. Write a SQL query to find the average salary per department.
Example Input:
| employee_id | first_name | last_name | salary | department_id |
|---|---|---|---|---|
| 101 | William | Walace | 50000 | 1 |
| 102 | Susan | Saradon | 75000 | 2 |
| 103 | Rick | Rimes | 65000 | 1 |
| 104 | Daniel | Doe | 55000 | 3 |
| 105 | Jane | Doe | 70000 | 2 |
Example Output:
| department_id | avg_salary |
|---|---|
| 1 | 57500 |
| 2 | 72500 |
| 3 | 55000 |
Answer:
The above query groups records by using the clause, and then for each group, the aggregate function is applied to calculate the average salary.
Applied SQL Interview Tips
The best way to prepare for a SQL interview, besides making sure you have strong SQL fundamentals, is to practice a ton of real SQL questions that were asked in recent job interviews. Beyond just solving the earlier Applied SQL interview questions, you should also solve the 200+ SQL exercises on DataLemur which come from companies like Meta, Google and industrial and electrical distribution companies like Applied.
Each SQL question has hints to guide you, detailed solutions and most importantly, there's an online SQL coding environment so you can instantly run your query and have it graded.
To prep for the Applied SQL interview it is also helpful to solve interview questions from other industrial and electrical distribution companies like:
- MSC Industrial Direct SQL questions
- Fastenal SQL questions
- Veritiv SQL questions
- Boise Cascade SQL questions
But if your SQL coding skills are weak, forget about jumping right into solving questions – refresh your SQL knowledge with this SQL tutorial for Data Analytics.
This tutorial covers SQL concepts such as AND/OR/NOT and filtering data with WHERE – both of these show up frequently in SQL interviews at Applied.
Applied Industrial Technologies Data Science Interview Tips
What Do Applied Data Science Interviews Cover?
In addition to SQL interview questions, the other types of questions covered in the Applied Data Science Interview are:
- Statistics and Probability Questions
- Python or R Programming Questions
- Analytics and Product-Metrics Questions
- ML Interview Questions
- Behavioral Interview Questions centered on Applied cultural values
How To Prepare for Applied Data Science Interviews?
To prepare for Applied Data Science interviews read the book Ace the Data Science Interview because it's got:
- 201 interview questions taken from Facebook, Google, & Amazon
- a refresher covering SQL, Product-Sense & ML
- over 1000+ reviews on Amazon & 4.5-star rating
Don't forget about the behavioral interview – prepare for that using this Behavioral Interview Guide for Data Scientists.