10 Hill-Rom Holdings SQL Interview Questions (Updated 2024)
Hill-Rom Holdings employees write SQL queries to analyze patient data, helping them identify trends in patient recovery times and device performance. It also allows them to enhance the efficiency of their devices and predict when equipment will need maintenance, ensuring that healthcare providers can rely on their products without interruption, this is why Hill-Rom Holdings asks SQL questions during interviews for Data Science, Data Engineering, and Data Analytics jobs.
Thus, to help you ace the Hill-Rom Holdings SQL interview, here's 10 Hill-Rom Holdings SQL interview questions in this blog.
10 Hill-Rom Holdings SQL Interview Questions
SQL Question 1: Identify Top Purchasing Customers at Hill-Rom Holdings
Hill-Rom Holdings wants to identify their "whale customers". These are the customers who have made the most numerous and highest value purchases within a given period of time – let's say over the last 12 months. Write a SQL query that will find these whale customers.
Consider the following table definitions:
Example Input:
| order_id | customer_id | purchase_date | product_id | order_amount |
|---|---|---|---|---|
| 101 | 321 | 01/05/2021 | 20001 | 3500.00 |
| 102 | 254 | 03/09/2021 | 21003 | 2500.00 |
| 103 | 101 | 05/12/2021 | 20005 | 2200.50 |
| 104 | 321 | 06/15/2021 | 20001 | 3500.00 |
| 105 | 254 | 07/18/2021 | 20004 | 1500.75 |
| 106 | 101 | 09/01/2021 | 21002 | 1800.90 |
| 107 | 321 | 11/10/2021 | 21003 | 2500.00 |
| 108 | 101 | 12/15/2021 | 20001 | 3500.00 |
Answer:
Here's a PostgreSQL query that would do it:
This query first filters the order data to only include orders made within the last 12 months. It then groups the remaining orders by and calculates two measures per customer: the count of orders they've made and the sum of all order amounts they've paid. Finally, the query sorts the customers by these two measures in descending order and only returns the top 5 customers - i.e. Hill-Rom's whale customers.
To practice a similar customer analytics SQL question where you can solve it right in the browser and have your SQL solution instantly graded, try this Walmart SQL Interview Question:
Discover how Hill-Rom Holdings is using innovative technology to enhance patient mobility in the ICU, ensuring better recovery outcomes! This information is crucial for grasping how advancements in healthcare technology can improve patient experiences and overall care quality.
SQL Question 2: Second Highest Salary
Suppose there was a table of Hill-Rom Holdings employee salary data. Write a SQL query to find the 2nd highest salary among all employees.
Hill-Rom Holdings Example Input:
| employee_id | salary |
|---|---|
| 1 | 2500 |
| 2 | 800 |
| 3 | 1000 |
| 4 | 1200 |
Example Output:
| second_highest_salary |
|---|
| 1200 |
You can solve this problem interactively on DataLemur:
Answer:
You can find a detailed solution with hints here: 2nd Highest Salary.
SQL Question 3: What's the difference between a correlated and non-correlated sub-query?
A correlated sub-query is one that relies on the outer query and cannot be run independently. It uses the outer query to filter or transform data by referencing a column from it, while the outer query uses the results of the inner query. On the other hand, a non-correlated sub-query is not linked to the outer query and can be run on its own. It does not reference any columns from the outer query and is used to retrieve additional data for the outer query.
An example correlated sub-query:
This correlated subquery retrieves the names and salaries of Hill-Rom Holdings employees who earn more than the average salary in their department. The subquery references the column in the main query's clause () and uses it to filter rows in the subquery's clause ().
An example non-correlated sub-query:
This non-correlated subquery retrieves the names and salaries of Hill-Rom Holdings employees who make more than the average salary for the Data Analytics department (which honestly should be very few people since Data Analysts are awesome).
Anyways, the subquery is independent of the main query and can be considered a standalone query. Its output (the average salary for the Data Analytics department) is then used in the main query to filter the rows of the table.
SQL Question 4: Analyzing medical equipment usage and maintenance
Hill-Rom Holdings is a global medical technology company. They have different types of medical equipment placed in various hospitals. They have a maintenance schedule to keep track of the usage and maintenance of the medical equipment.
Consider the following schema for the table which records each equipment use and maintenance event by date.
Example Input:
| id | equipment_id | event_date | event_type | hospital_id |
|---|---|---|---|---|
| 1 | E101 | 2022-01-15 | usage | H001 |
| 2 | E102 | 2022-01-16 | usage | H002 |
| 3 | E101 | 2022-02-01 | maintenance | H001 |
| 4 | E101 | 2022-02-15 | usage | H001 |
| 5 | E102 | 2022-03-01 | maintenance | H002 |
Your task is to write a SQL query that retrieves the , and the number of days passed since the last maintenance for each usage event. The rows should be sorted by in ascending order.
You can assume that maintenance always happens before usage and if a piece of equipment has been used without a prior maintenance, simply return NULL for that piece of equipment.
Example Output:
| equipment_id | hospital_id | days_since_last_maintenance |
|---|---|---|
| E101 | H001 | NULL |
| E102 | H002 | NULL |
| E101 | H001 | 15 |
| E101 | H001 | 14 |
Answer:
The question can be solved using SQL window functions which allow calculations across set of rows related to current row. Here, the solution uses the function:
In the above SQL block, the window function is used to get the date of the last event for each piece of equipment at each hospital. Then the number of days till the current usage from the last maintenance is calculated. If the current event is a maintenance, NULL is returned as instructed.
To practice another window function question on DataLemur's free online SQL code editor, try this Google SQL Interview Question:
SQL Question 5: Do NULLs in SQL mean the same thing as a zero?
In SQL, zero's are numerical values which can be used in calculations and comparisons just like any other number. A blank space, also known as an empty string, is a character value and can be used in character manipulation functions and comparisons.
NULLs aren't the same as zero's or blank spaces. NULLs represent unkonwn, missing, or not applicable values. They are not included in calculations and comparisons involving NULL values always result in NULL.
SQL Question 6: Medical Equipment Tracking and Utilization
Hill-Rom Holdings is a global medical technology company with products such as hospital beds, surgical tables, and patient lifts. Assume they have hospitals as customers and for each hospital, they lease a number of medical equipment which can be different types such as beds, tables, lifts, etc. Each of the equipment is identified by a unique equipment id, and it has different states (e.g., leased, under service, returned).
Hill-Rom would like you to design a database that tracks the different equipment leased to each hospital, with their current states. The business wants to know which hospital has the most "leased" equipment at the moment. Please provide the SQL query to answer this.
Here's how the database tables could be designed:
Example Input:
| hospital_id | hospital_name |
|---|---|
| 1 | Hospital A |
| 2 | Hospital B |
| 3 | Hospital C |
Example Input:
| equipment_id | equipment_type | state | hospital_id |
|---|---|---|---|
| 1001 | bed | leased | 1 |
| 1002 | table | under service | 1 |
| 1003 | lift | returned | 2 |
| 1004 | bed | leased | 1 |
| 1005 | bed | leased | 2 |
| 1006 | lift | leased | 2 |
| 1007 | table | under service | 3 |
| 1008 | bed | leased | 3 |
Answer:
This query first joins the table with the table using the . It then filters the records where the of the equipment is 'leased'. The query groups the records by and counts the number of 'leased' equipment for each hospital. Finally, it orders the hospitals by the number of 'leased' equipment in descending order and limits the output to the hospital with the highest count.
SQL Question 7: Do and a typically produce equivalent results?
For all practical purposes, and do NOT produce the same results.
While both are similar in that they combine two tables, you can think of joins as increasing the width of the resulting table (you'll have more columns in the result set for a left/inner/right join), whereas a union is used to combine rows which increases the height of the result set but keeps the column count the same.
If your familiar with set operations, you can think of a as set addition, whereas a is set multiplication.
SQL Question 8: Average Usage Hours of Medical Equipment at Hill-Rom Holdings
Hill-Rom Holdings, a leading worldwide manufacturer and provider of medical technologies, collects data on the usage hours of their medical equipment installed at various customer locations. They require a SQL query to find the average usage hours per day for each piece of equipment in each location for the month of August 2022.
Assume the following tables.
Sample Input:
| usage_id | equipment_id | location_id | use_date | hours_used |
|---|---|---|---|---|
| 1001 | 201 | 001 | 08/01/2022 | 10 |
| 1002 | 202 | 002 | 08/02/2022 | 9 |
| 1003 | 201 | 001 | 08/02/2022 | 12 |
| 1004 | 201 | 001 | 08/03/2022 | 10 |
| 1005 | 202 | 002 | 08/03/2022 | 11 |
Example Output:
| location | equipment | avg_hours_per_day_Aug_2022 |
|---|---|---|
| 001 | 201 | 11 |
| 002 | 202 | 10 |
Answer:
This query selects the , and calculates the average for each piece of equipment in each location for dates in the month of August 2022. The clause is used to only include dates in August 2022, and GROUP BY is used to group the data by both location and equipment.
To practice a very similar question try this interactive Amazon Server Utilization Time Question which is similar for calculating usage time or this Alibaba Compressed Mean Question which is similar for calculating average based on data.
SQL Question 9: Calculate the Click-Through-Conversion Rate for Hill-Rom Holdings
Hill-Rom Holdings is a global medical technology company. Let's say it recently developed a new line of online medical products. They started an online ad campaign and want to analyze the click-through-conversion, specifically the rates of users clicking their digital ads to view a product page and eventually add a product to the cart.
You have two tables. The first is a table that logs every time a user clicks on an ad to view a product (). The second table is , which logs each time a product is added to a user's cart ().
Calculate the click-through-conversion rate, defined as the total number of unique users who added a product to their cart after viewing it from an ad (), divided by the total number of unique users who viewed a product from an ad ().
Example Input:
| click_id | user_id | view_product |
|---|---|---|
| 1001 | 500 | 06/08/2022 00:00:00 |
| 1002 | 501 | 06/10/2022 00:00:00 |
| 1003 | 502 | 06/18/2022 00:00:00 |
| 1004 | 502 | 07/26/2022 00:00:00 |
| 1005 | 503 | 07/05/2022 00:00:00 |
Example Input:
| add_id | user_id | add_to_cart |
|---|---|---|
| 2150 | 500 | 07/26/2022 00:00:00 |
| 2151 | 501 | 06/10/2022 00:00:00 |
| 2152 | 502 | 06/18/2022 00:00:00 |
| 2153 | 504 | 07/05/2022 00:00:00 |
Answer:
The SQL query will the and tables on . It will count the number of distinct in both tables, which denotes the total unique users who viewed a product from an ad and the total unique users who added a product to their cart after viewing it from an ad, respectively. The click-through-conversion rate is calculated as the number of unique users adding a product to their cart divided by the number of unique users viewing a product from an ad.
To practice another question about calculating rates, solve this TikTok SQL Interview Question within DataLemur's interactive coding environment:
SQL Question 10: What does it mean to perform a self-join?
A self-join is a type of where a table is joined to itself. To execute a self-join, you must include the table name twice in the clause and assign a different alias to each instance. You can then join the two copies of the table using a clause and use a clause to specify the relationship between the rows.
One common use case for self-joins is to compare data within a single table. For example, you might use a self-join to compare the salaries of employees within the same department, or to identify pairs of products that are frequently purchased together (like in this real Walmart SQL interview question)[https://datalemur.com/questions/frequently-purchased-pairs].
For a more concrete example, imagine you had website visitor data for Hill-Rom Holdings, exported from the company's Google Analytics account. To help the web-dev team, you needed to analyze pairs of pages for UX or navigational issues. As part of that analysis, you wanted to produce all pairs of URLs, but needed to exclude pairs where both URLs were the same since that is not a valid pair.
You could use the following self-join:
This query retrieves the url of each page () along with the url of the page that referred to it (). The self-join is performed using the , which identifies the id of the page that referred the visitor to the current page, and excludes any pages that referred to themselves (i.e., data anomalies since pages shouldn't refer to themself).
Preparing For The Hill-Rom Holdings SQL Interview
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. In addition to solving the earlier Hill-Rom Holdings SQL interview questions, you should also solve the 200+ SQL coding questions which come from companies like Microsoft, Google, Amazon, and tech startups.
Each problem on DataLemur has hints to guide you, detailed solutions and best of all, there is an online SQL coding environment so you can right online code up your SQL query answer and have it executed.
To prep for the Hill-Rom Holdings SQL interview you can also be wise to practice interview questions from other healthcare and pharmaceutical companies like:
- Change Healthcare SQL questions
- ResMed SQL questions
- IDEXX Laboratories SQL questions
- Option Care Health SQL questions
However, if your SQL coding skills are weak, forget about jumping right into solving questions – go learn SQL with this free SQL tutorial.
This tutorial covers topics including creating summary stats with GROUP BY and filtering data with WHERE – both of which show up often during Hill-Rom Holdings SQL interviews.
Hill-Rom Holdings Data Science Interview Tips
What Do Hill-Rom Holdings Data Science Interviews Cover?
Beyond writing SQL queries, the other types of problems to prepare for the Hill-Rom Holdings Data Science Interview include:
- Statistics & Probability Questions
- Python Pandas or R Coding Questions
- Product Metrics Interview Questions
- ML Modelling Questions
- Behavioral & Resume-Based Questions
How To Prepare for Hill-Rom Holdings Data Science Interviews?
I think the best way to prep for Hill-Rom Holdings Data Science interviews is to read the book I wrote: Ace the Data Science Interview.
It has 201 data interview questions sourced from FAANG, tech startups, and Wall Street. The book's also got a crash course covering SQL, AB Testing & ML. And finally it's helped thousands of people land their dream job in data, which is why it's earned 1000+ reviews on Amazon and a 4.5-star rating.
While the book is more technical in nature, it's also key to prepare for the Hill-Rom Holdings behavioral interview. A good place to start is by reading the company's cultural values.