8 Centene SQL Interview Questions (Updated 2024)
At Centene, SQL is essential for analyzing healthcare data trends, allowing them to better understand patient needs and enhance service delivery. They also use SQL to streamline insurance claim processes, making it easier for beneficiaries to get the support they need, that is why Centene asks SQL query questions during interviews for Data Science, Data Engineering, and Data Analytics positions.
So, to help you prep, we've collected 8 Centene SQL interview questions – can you solve them?
8 Centene SQL Interview Questions
SQL Question 1: Rank Patient by Cost
Centene would like to analyze patients' medical records and expenses. Please write a SQL query to rank patients by the total cost of all their medical treatments within a certain period, let's assume it's the year 2021. Use the window function to calculate the rank. The top rank should be the patient who has the maximum total cost.
Assume you are given a table named containing the specified patients' medical records with columns , , , and , where:
- is the unique id for the medical record,
- is the id of the patient,
- is the date of the treatment, and
- is the cost of the medical treatment.
Example Input:
| record_id | patient_id | treatment_date | cost |
|---|---|---|---|
| 1 | 100 | 01/01/2021 | 500 |
| 2 | 101 | 03/07/2021 | 200 |
| 3 | 100 | 04/10/2021 | 300 |
| 4 | 102 | 05/10/2021 | 250 |
| 5 | 101 | 06/14/2021 | 600 |
| 6 | 102 | 07/19/2021 | 400 |
| 7 | 100 | 08/09/2021 | 200 |
| 8 | 102 | 12/20/2021 | 350 |
Answer:
This query calculates the total cost of medical treatments for each patient within the year 2021. Then, it ranks the patients based on the total cost in descending order using the window function. The patient who has the maximum total cost gets the top rank. The result would include 3 columns: patient id, total cost, and the rank. It will be sorted by rank in ascending order.
For more window function practice, solve this Uber SQL problem within DataLemur's interactive SQL code editor:
Delve into Centene's commitment to corporate sustainability and innovation, showcasing how they are using technology to empower better health outcomes! Learning about their initiatives can help you appreciate the role of innovation in improving healthcare delivery and accessibility.
SQL Question 2: Department vs. Company Salary
Suppose you had a table of Centene employee salary data, along with which department they were in. Write a query to compare the average salary of employees in each department to the company's average salary. Return the comparison result as 'higher', 'lower', or 'same' for each department. Display the department ID, payment month (in MM-YYYY format), and the comparison.
Write a SQL query for this interview question interactively on DataLemur:
The solution is LONG – 30+ lines of SQL. You can find a step-by-step solution with hints here: Department vs. Company Salary.
SQL Question 3: What's the difference between a foreign and primary key?
To explain the difference between a primary key and foreign key, let's start with an example Centene sales database:
:
| order_id | product_id | customer_id | quantity |
|---|---|---|---|
| 1 | 303 | 1 | 2 |
| 2 | 404 | 1 | 1 |
| 3 | 505 | 2 | 3 |
| 4 | 303 | 3 | 1 |
In this table, could be a primary key. It is unique for each row in the table and cannot contain null values.
and could both be foreign keys. They reference the primary keys of other tables, such as a Products table and a Customers table, respectively. This establishes a relationship between the table and the other tables, such that each row in the sales database corresponds to a specific product and a specific customer.
SQL Question 4: Calculate the average claims per policy
Centene is a large multi-national healthcare company. Can you find the average number of claims per policy for each insurance category?
Example Input:
| claim_id | policy_id | claim_date | amount |
|---|---|---|---|
| 101 | 123 | 2022-01-15 | 500.00 |
| 102 | 123 | 2022-02-20 | 150.00 |
| 103 | 456 | 2022-01-10 | 200.00 |
| 104 | 456 | 2022-03-05 | 180.00 |
| 105 | 789 | 2022-04-17 | 250.00 |
Example Input:
| policy_id | user_id | category | start_date | end_date |
|---|---|---|---|---|
| 123 | 123 | Dental | 2021-12-01 | 2022-12-01 |
| 456 | 456 | Vision | 2022-01-01 | 2023-01-01 |
| 789 | 789 | Health | 2022-03-01 | 2023-03-01 |
Answer:
The subquery counts how many claims there are for each single policy. For calculating the average number of claims per policy, the count of claims (grouped by each policy_id) is joined with the policies table to bring in the policy's insurance category. This allows calculation of the mean number of claims for each policy, separated by insurance category. The AVG function is used to evaluate this average. This result gives us the desired average number of claims per policy, outlined by each insurance category.
To practice a very similar question try this interactive Amazon Average Review Ratings Question which is similar for calculating averages or this Stripe Repeated Payments Question which is similar for dealing with multiple occurrences.
SQL Question 5: In the context of a database transaction, what does ACID 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 6: Analyzing Click-Through Rates for Centene
Centene is a multinational healthcare company. They are showing health plans on their website, and they want to study the click-through rates. Specifically, they want to monitor the number of users who viewed a health plan and then clicked to see more details.
You have been given two tables - and . The table contains data about which user viewed what plan when, and the table records instances when the user clicked on a plan to see more information.
Our Task: Determine the click-through rate for each health plan for the month of September 2022, i.e., the number of unique users who clicked to see a plan's details divided by the total unique viewers for that plan.
Sample Input:
| view_id | user_id | view_date | plan_id |
|---|---|---|---|
| 371 | 100 | 09/02/2022 00:00:00 | 401 |
| 872 | 201 | 09/07/2022 00:00:00 | 401 |
| 562 | 301 | 09/15/2022 00:00:00 | 402 |
| 933 | 100 | 09/20/2022 00:00:00 | 402 |
| 475 | 400 | 09/23/2022 00:00:00 | 403 |
Sample Input:
| click_id | user_id | click_date | plan_id |
|---|---|---|---|
| 9201 | 100 | 09/02/2022 00:00:00 | 401 |
| 6802 | 500 | 09/10/2022 00:00:00 | 401 |
| 7293 | 301 | 09/18/2022 00:00:00 | 402 |
| 9352 | 400 | 09/23/2022 00:00:00 | 403 |
| 8517 | 600 | 09/25/2022 00:00:00 | 403 |
Solution:
In this solution, we are using PostgreSQL's function to limit our analysis to September 2022. A combines the and tables, matching them on both and . Lastly, we are getting the unique count of users who viewed each plan and those who clicked on them, and dividing the latter by the former to get the click-through rate.
To solve a related problem on DataLemur's free interactive SQL code editor, solve this Facebook SQL Interview question:
SQL Question 7: What's a self-join, and when would you use one?
A self-join is a type of JOIN where a table is joined to itself. To execute a self-join, you must include the table name twice in the FROM clause and assign a different alias to each instance. You can then join the two copies of the table using a JOIN clause, and use a WHERE 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 Centene, 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).
SQL Question 8: Aggregating Patient Information
As a healthcare IT company, Centene would often need to analyze various metrics related to patient care. Consider a scenario where Centene needs to determine the average treatment cost and total number of patients per healthcare provider, grouped by provider's specialty.
Assume the table contains patient information, while table logs each treatment provided to the patients by different healthcare providers.
Example Input:
| patient_id | provider_id |
|---|---|
| 1 | 100 |
| 2 | 101 |
| 3 | 100 |
| 4 | 102 |
| 5 | 102 |
Example Input:
| provider_id | specialty |
|---|---|
| 100 | Cardiology |
| 101 | Dermatology |
| 102 | Cardiology |
Example Input:
| patient_id | treatment_cost |
|---|---|
| 1 | 5000 |
| 2 | 200 |
| 3 | 5500 |
| 4 | 7000 |
| 5 | 6000 |
Based on this information, create a PostgreSQL query that generates this output:
Example Output:
| Specialty | Avg_treatment_cost | Total_patients |
|---|---|---|
| Cardiology | 5875 | 3 |
| Dermatology | 200 | 1 |
Answer:
The PostgreSQL query would look like this:
This query first joins the , , and tables on the relevant columns ( and ). It then groups the result by in the table. The function is used to calculate the average treatment cost and function is used to count the total distinct patients for each specialty.
Preparing For The Centene SQL Interview
Assuming that you've already got basic SQL skills, the next best tip we have to prepare for the Centene SQL interview is to solve as many practice SQL interview questions as you can! In addition to solving the earlier Centene SQL interview questions, you should also solve the 200+ tricky sql questions on DataLemur which come from companies like tech companies and healthcare and pharmaceutical companies like Centene.
Each interview question has hints to guide you, step-by-step solutions and best of all, there is an interactive SQL code editor so you can right online code up your query and have it graded.
To prep for the Centene SQL interview you can also be useful to solve interview questions from other healthcare and pharmaceutical companies like:
- Elevance Health SQL questions
- Cardinal Health SQL questions
- Cigna SQL questions
- AmerisourceBergen SQL questions
But if your SQL query skills are weak, don't worry about jumping right into solving questions – refresh your SQL knowledge with this DataLemur SQL tutorial.
This tutorial covers SQL topics like math functions like ROUND()/CEIL() and Subquery vs. CTE – both of these come up routinely during Centene interviews.
Centene Data Science Interview Tips
What Do Centene Data Science Interviews Cover?
In addition to SQL interview questions, the other topics tested in the Centene Data Science Interview include:
- Probability & Stats Questions
- Coding Questions in Python or R
- Open-Ended Data Case Studies
- ML Modelling Questions
- Behavioral Interview Questions
How To Prepare for Centene Data Science Interviews?
To prepare for the Centene Data Science interview have a firm understanding of the company's cultural values – this will be clutch for acing the behavioral interview. For technical interviews prepare by reading Ace the Data Science Interview. The book's got:
- 201 Interview Questions from Facebook, Google, & Amazon
- A Refresher on SQL, Product-Sense & ML
- Great Reviews (1000+ reviews, 4.5-star rating)