11 Liberty Mutual SQL Interview Questions (Updated 2024)

Updated on

August 11, 2024

Data Analytics, Data Science, and Data Engineering employees at Liberty Mutual uses SQL to analyze claim data, including claim frequencies and severities, for fraud detection, as well as organizing customer data, such as demographics and policy information, for personalized insurance offering. For this reason, Liberty Mutual often uses SQL questions for job interviews.

Data Analytics, Data Science, and Data Engineering employees at Liberty Mutual write ad-hoc SQL queries as a big part of their job. They use SQL for analyzing claim data for fraud detection and organizing customer data for personalized insurance offering. For this reason Liberty Mutual often tests jobseekers SQL interview questions.

Thus, to help you study for the Liberty Mutual SQL interview, we've curated 11 Liberty Mutual Insurance Group SQL interview questions in this article.

Liberty Mutual SQL Interview Questions

11 Liberty Mutual Insurance Group SQL Interview Questions

SQL Question 1: Identify Top Insurance Policy Holders

Liberty Mutual wants to identify their "power users", that is, the users who have the most active insurance policies and pay their premiums regularly and on time. You are tasked to write a SQL query to find the top 10 users with the most active insurance policies, and also make sure that these users haven't missed any premium payments in the last 12 months.

Consider the following two tables: and .

Example Input:
policy_idholder_idactive_sincepremium_amount
40112701/01/2019500
49032506/30/2020700
51012705/05/2020800
60031204/20/2019600
76032512/25/2020400
Example Input:
payment_idpolicy_idpayment_dateamount_paid
610140101/01/2020500
610240102/01/2020500
610351003/01/2020800
610440104/01/2020500
610551005/01/2020800

Answer:

You can use PostgreSQL's window function to count the number of active policies per user, then filter out those who have missed any payments in the last 12 months.


This query first counts the number of active policies per user. It then identifies any policy_id with missed or no payment made in the last 12 months. Finally, it filters out users who have any missed payments and orders the remaining users by the number of policies in descending order. The 'LIMIT 10' then provides us with our top 10 power users.

To work on a similar customer analytics SQL question where you can solve it right in the browser and have your SQL code instantly executed, try this Walmart Labs SQL Interview Question: Walmart Labs SQL Interview Question

SQL Question 2: Top Three Salaries

Given a table of Liberty Mutual employee salary information, write a SQL query to find the top 3 highest earning employees in each department.

Liberty Mutual Example Input:

employee_idnamesalarydepartment_id
1Emma Thompson38001
2Daniel Rodriguez22301
3Olivia Smith20001
4Noah Johnson68002
5Sophia Martinez17501
8William Davis68002
10James Anderson40001

Example Input:

department_iddepartment_name
1Data Analytics
2Data Science

Example Output:

department_namenamesalary
Data AnalyticsJames Anderson4000
Data AnalyticsEmma Thompson3800
Data AnalyticsDaniel Rodriguez2230
Data ScienceNoah Johnson6800
Data ScienceWilliam Davis6800

Check your SQL query for this problem interactively on DataLemur:

Top 3 Department Salaries

Answer:

We use the DENSE_RANK() window function to generate unique ranks for each employee's salary within their department, with higher salaries receiving lower ranks. Then, we wrap this up in a CTE and filter the employees with a ranking of 3 or lower.


If the code above is hard to understand, you can find a detailed solution with hints here: Top 3 Department Salaries.

SQL Question 3: What are the differences between an inner and a full outer join?

An inner join returns only the rows that match the join condition between the two tables, whereas a full outer join returns all rows from both tables, including any unmatched rows.

Example:

Example:

Liberty Mutual Insurance Group SQL Interview Questions

SQL Question 4: Calculate Monthly Average Star Rating for Each Insurance Policy

Liberty Mutual being an insurance company, requires analysis around its insurance policy reviews. Imagine, the company wishes to track the average star rating received for each insurance policy on a monthly basis, based on customer reviews. To facilitate this, there is a dataset containing information for each review submitted for the various insurance policies available.

Please write a SQL query to calculate the monthly average star rating received for each insurance policy.

Example Input:
review_iduser_idsubmit_datepolicy_idstars
61711232022-06-08500014
78022652022-06-10698524
52933622022-06-18500013
63521922022-07-26698523
45179812022-07-05698522

Answer:

In PostgreSQL, this can be solved using the window function with a clause.


The above query first truncates the submit date to month using , which serves as the basis for partitioning the data. Then, the clause partitions the data by both the month and policy_id. After partitioning, the function calculates the average stars for each partition.

Example Output:
monthpolicy_idavg_stars
2022-06-01 00:00:00500013.50
2022-06-01 00:00:00698524.00
2022-07-01 00:00:00698522.50

Pro Tip: Window functions are a popular SQL interview topic, so practice every window function problem on DataLemur

DataLemur Window Function SQL Questions

SQL Question 5: How do foreign and primary keys differ?

A primary key is a column (or set of columns) in a table that uniquely identifies each row in the table. It cannot contain null values and must be unique across all rows in the table.

A foreign key is a column (or set of columns) in a table that references the primary key of another table. It is used to establish a relationship between the two tables. A foreign key can contain null values, and multiple rows in the referencing table can reference the same row in the referenced table.

For example, consider a database with two tables: and . The Liberty Mutual customers table might have a primary key column called , while the Liberty Mutual orders table might have a foreign key column called that references the column in the table. This establishes a relationship between the two tables, such that each row in the orders table corresponds to a specific Liberty Mutual customer.

SQL Question 6: Liberty Mutual's Claims Processing

Liberty Mutual, a global insurance company, wants to see how efficient they are in processing their insurance claims. Your task is to design a database for storing these claims, model the tables and their relationships, and then write an SQL query to calculate the average processing time for claims per claim type for the year 2022.

Let's assume we have two tables namely and :

Example Input:
claim_idpolicy_holder_idclaim_type_idclaim_submit_dateclaim_resolve_date
101234532022-03-252022-04-05
102456722022-05-012022-05-25
103874512022-06-102022-07-11
104234532022-07-232022-07-29
105874512022-12-052023-01-01
Example Input:
claim_type_idclaim_type_name
1Vehicle
2Home
3Personal Injury

Answer:


This query calculates the average processing time (in days) by taking the difference between the claim resolve date and the claim submit date. It then averages these differences per claim type over the course of the year 2022.

SQL Question 7: What does the SQL keyword do?

If you want to return records with no duplicates, you can use the keyword in your statement.

For example, if you had a table of Liberty Mutual employees, and wanted to see what are all the unique job titles that currently worked at the company, you could write the following query:


If had the following data:

f_namejob_title
AkashData Analyst
BrittanyData Scientist
CarlosData Engineer
DiegoData Engineer
EvaData Analyst

Then the output from the query would be:

job_title
Data Analyst
Data Scientist
Data Engineer

SQL Question 8: Calculate the Average Premium for Each Insurance Category

Liberty Mutual being an insurance company, a relevant question might be to calculate the average premium customers are paying for each category of insurance provided by the company.

Let's consider a table which represents the policies taken by the customers:

Sample Input:
policy_idcustomer_idcategorypremium
001123Auto1000
002265Home1500
003362Auto1200
004192Life5000
005981Home2000

The question is: Write a SQL query to find the average premium customers are paying for each category of insurance.

Answer:


This query would group the table by , and for each one, it calculates the average value of the column. This could be useful in analyzing which insurance categories have the highest average cost, which could, in turn, provide insights into patterns in sales and customer behavior.

Sample Output:
categoryavg_premium
Auto1100
Home1750
Life5000

To practice a very similar question try this interactive Amazon Highest-Grossing Items Question which is similar for calculating average per category or this CVS Health Pharmacy Analytics (Part 1) Question which is similar for identifying top items in each category.

SQL Question 9: Calculate the Total and Average Premium for Each Insurance Type

As an analyst for Liberty Mutual, one of your roles is to understand the payment behavior of customers, especially regarding different types of insurance.

For this task, you are given access to the table that contains historical data about customers' insurance types and their respective premiums. Your task is to write an SQL query to find out the total and average premiums for each insurance type.

Example Input:
insurance_idcustomer_idtypepremium
101321Home1500
102654Auto1200
103789Life900
104654Auto1300
105321Home1700
106789Life1100

Answer:

To answer this question, you can write an SQL query using and the aggregate functions and as follows:


This query first groups the data by the insurance type. It then calculates the total premium and the average premium for each group.

The calculates the total premium of every type of insurance for all customers, while calculates the average premium for each insurance type.

Finally, the results are presented in a table with , and columns.

Example Output:
typetotal_premiumaverage_premium
Auto25001250
Home32001600
Life20001000

SQL Question 10: Can you describe the difference between a unique and a non-unique index?

Unique indexes help ensure that there are no duplicate key values in a table, maintaining data integrity. They enforce uniqueness whenever keys are added or changed within the index.

To define a unique index in PostgreSQL, you can use the following syntax:


To define a non-unique index in PostgreSQL, you can use the following syntax:

Non-unique indexes on the other hand, are used to improve query performance by maintaining a sorted order of frequently used data values, but they do not enforce constraints on the associated table.


SQL Question 11: Retrieving Policy Holders from Specific City

At Liberty Mutual, you are tasked to retrieve customer profiles whose addresses mention a specific city, for instance, 'Boston'. Such records are crucial for evaluations related to geographical distribution and region-specific plans.

Consider the table with the following structure:

Example Input:
profile_idholder_nameaddresspolicy_number
101John Doe35 N. Beacon St, Boston, MA 02215MA001
102Jane Smith120 Tremont St, Boston, MA 02108MA002
103Mike Davis1 Beach St, Unit 2, New York, NY 10011NY001
104Sara Elsa51 Chauncy St, Apt# 4, Boston, MA 02111MA003
105David Watson279 W. 113rd St, Apt 3A, New York, NY 10026NY002

Please write a PostgreSQL query to retrieve only the records of policy holders who live in 'Boston'.

Answer:


This query will return all rows from the table where the field contains the string 'Boston'. The percent (%) symbol is used in conjunction with the LIKE operator to denote an unknown number or characters before and after 'Boston'.

The output will be:

profile_idholder_nameaddresspolicy_number
101John Doe35 N. Beacon St, Boston, MA 02215MA001
102Jane Smith120 Tremont St, Boston, MA 02108MA002
104Sara Elsa51 Chauncy St, Apt# 4, Boston, MA 02111MA003

Preparing For The Liberty Mutual SQL Interview

The key to acing a Liberty Mutual SQL interview is to practice, practice, and then practice some more! Beyond just solving the earlier Liberty Mutual SQL interview questions, you should also solve the 200+ SQL Interview Questions on DataLemur which come from companies like Netflix, Airbnb, and Amazon.

DataLemur SQL and Data Science Interview Questions

Each DataLemur SQL question has hints to guide you, step-by-step solutions and most importantly, there is an interactive coding environment so you can instantly run your query and have it executed.

To prep for the Liberty Mutual SQL interview it is also a great idea to practice interview questions from other insurance companies like:

Read about Liberty Mutual's exciting new collaboration with MIT to drive AI innovation in the insurance industry!

However, if your SQL foundations are weak, don't worry about jumping right into solving questions – refresh your SQL knowledge with this DataLemur SQL tutorial.

DataLemur SQL Tutorial for Data Science

This tutorial covers SQL topics like creating summary stats with GROUP BY and LEAD window function – both of these show up frequently in Liberty Mutual SQL interviews.

Liberty Mutual Insurance Group Data Science Interview Tips

What Do Liberty Mutual Data Science Interviews Cover?

Beyond writing SQL queries, the other types of problems to practice for the Liberty Mutual Data Science Interview include:

Liberty Mutual Data Scientist

How To Prepare for Liberty Mutual Data Science Interviews?

To prepare for Liberty Mutual Data Science interviews read the book Ace the Data Science Interview because it's got:

  • 201 interview questions sourced from FAANG (FB, Apple, Amazon, Netflix, Google)
  • a refresher covering Stats, ML, & Data Case Studies
  • over 1000+ reviews on Amazon & 4.5-star rating

Acing Data Science Interview

Don't ignore the behavioral interview – prep for it with this list of behavioral interview questions for Data Scientists.

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