8 Western & Southern SQL Interview Questions (Updated 2024)
Data Analysts & Data Scientists at Western & Southern uses SQL to analyze financial data trends, including investment portfolio performance and market analysis, as well as performing predictive modeling on client behaviors, such as predicting policy lapse rates. That is why Western & Southern frequently asks SQL questions during job interviews.
So, to help you study, we've curated 8 Western & Southern Financial Group SQL interview questions – how many can you solve?
8 Western & Southern Financial Group SQL Interview Questions
SQL Question 1: Revenue Analysis with Window Function
Assume you work for Western & Southern, an insurance and investment group. Your manager wants you to analyze the company's life insurance sales. You're given the following two tables:
Table:
| agent_id | agent_name | region |
|---|---|---|
| 1 | John Doe | West |
| 2 | Jane Smith | East |
| 3 | Mary Johnson | South |
| 4 | James Brown | North |
Table:
| sale_id | agent_id | sale_date | product | quantity | price |
|---|---|---|---|---|---|
| 101 | 1 | 2022-08-01 | Life Insurance | 10 | 50 |
| 102 | 2 | 2022-08-05 | Life Insurance | 8 | 60 |
| 103 | 3 | 2022-08-10 | Life Insurance | 12 | 45 |
| 104 | 4 | 2022-08-15 | Life Insurance | 9 | 55 |
| 105 | 1 | 2022-08-18 | Life Insurance | 7 | 50 |
Please write a SQL query to analyze the running total sales revenue for life insurance product by each sales agent within their region. You need to return the , , , and .
Answer:
Here is a PostgreSQL query you can use:
In this query, a window function is used to calculate the running total of sales revenue for each agent. is used to segment the sales data for running sums separately for each agent. is used to process the sales in chronological order. The WHERE clause restricts the data to life insurance product only.
To solve a related window function SQL problem on DataLemur's free online SQL coding environment, try this Google SQL Interview Question:
SQL Question 2: Second Highest Salary
Given a table of Western & Southern employee salaries, write a SQL query to find the 2nd highest salary at the company.
Western & Southern Example Input:
| employee_id | salary |
|---|---|
| 1 | 2500 |
| 2 | 800 |
| 3 | 1000 |
| 4 | 1200 |
Example Output:
| second_highest_salary |
|---|
| 1200 |
Check your SQL query for this problem and run your code right in the browser:
Answer:
You can find a step-by-step solution here: 2nd Highest Salary.
SQL Question 3: What are SQL constraints, and can you give some examples?
Constraints are just rules for your DBMS to follow when updating/inserting/deleting data.
Say you had a table of Western & Southern employees, and their salaries, job titles, and performance review data. Here's some examples of SQL constraints you could implement:
NOT NULL: This constraint could be used to ensure that certain columns in the employee table, such as the employee's first and last name, cannot contain NULL values.
UNIQUE: This constraint could be used to ensure that the employee ID is unique. This would prevent duplicate entries in the employee table.
PRIMARY KEY: This constraint could be used to combine the NOT NULL and UNIQUE constraints to create a primary key for the employee table. The employee ID could serve as the primary key.
FOREIGN KEY: This constraint could be used to establish relationships between the employee table and other tables in the database. For example, you could use a foreign key to link the employee ID to the department ID in a department table to track which department each employee belongs to.
CHECK: This constraint could be used to ensure that certain data meets specific conditions. For example, you could use a CHECK constraint to ensure that salary values are always positive numbers.
DEFAULT: This constraint could be used to specify default values for certain columns. For example, you could use a DEFAULT constraint to set the employee hire date to the current date if no value is provided when a new employee is added to the database.
SQL Question 4: Average Policy Premium of Each Insurance Type
Western & Southern is a financial services company that offers various types of insurances. Write a SQL query to find the average premium for each type of insurance policy sold by Western & Southern.
Example Input:
| policy_id | customer_id | start_date | insurance_type | premium |
|---|---|---|---|---|
| 001 | 123 | 01/01/2022 | Life Insurance | 5000 |
| 002 | 456 | 05/01/2022 | Health Insurance | 3000 |
| 003 | 789 | 07/13/2022 | Car Insurance | 3500 |
| 004 | 321 | 02/16/2022 | Life Insurance | 6000 |
| 005 | 654 | 03/12/2022 | Car Insurance | 4000 |
Example Output:
| Insurance Type | Average Premium |
|---|---|
| Life Insurance | 5500 |
| Health Insurance | 3000 |
| Car Insurance | 3750 |
Answer:
This query is using the AVG function to find the average premium for each type of insurance policy. The GROUP BY statement is used to group the results by the type of the insurance so that the average premium can be found for each type separately. The resulting values are aliases as "Average Premium".
To practice a very similar question try this interactive Amazon Average Review Ratings Question which is similar for calculating averages or this Alibaba Compressed Mean Question which is similar for handling financial data.
SQL Question 5: How do you determine which records in one table are not present in a second table?
To identify records in one table that do not appear in another, you can use a LEFT JOIN and examine NULL values in the right-side table.
Say for example you had exported Western & Southern's CRM (Customer Relationship Management) database into PostgreSQL, and had a table of sales leads, and a second table of companies.
Here's an example of how a query could find all sales leads that are not associated with a company:
This query brings back all rows from the sales leads table, along with any matching rows from the companies table. If there is no matching row in the companies table, NULL values will be returned for all of the right table's columns.
We then filter out out any rows where the column is , leaving only the sales leads that are NOT associated with a company.
SQL Question 6: Average Policy Premium by State
In Western & Southern, an insurance company, we issue different types of insurance policies to customers from various states in the U.S. For each policy, we collect a premium amount which can be different based on the policy type and customer's state. Your task is to write a SQL query to determine the average insurance policy premium by state for the current year.
Example Input:
| policy_id | customer_id | policy_type | issue_date | state | premium_amount |
|---|---|---|---|---|---|
| 1001 | 620 | Home | 2022-01-01 | CA | 1200 |
| 1002 | 520 | Life | 2022-02-15 | NY | 800 |
| 1003 | 320 | Car | 2022-05-25 | TX | 900 |
| 1004 | 620 | Life | 2022-03-01 | CA | 700 |
| 1005 | 785 | Home | 2022-06-20 | FL | 1500 |
Example Output:
| state | avg_premium |
|---|---|
| CA | 950 |
| NY | 800 |
| TX | 900 |
| FL | 1500 |
Answer:
This query first filters the policies for the current year using the 'EXTRACT' function. It then groups the filtered results by the state. For each group, it calculates the average premium amount, which is then returned as the result.
SQL Question 7: Can you explain what a cross-join is and the purpose of using them?
A cross-join, also known as a cartesian join, is a type of join that returns the cross-product of two tables. In a cross-join, each row from the first table is paired with every row from the second table, resulting in a new table that has a row for each possible combination of rows from the two input tables.
For example, say you worked on the Marketing Analytics team at Western & Southern, and needed to understand what advertising copy (text) goes best with what advertising creative (the photo that gets posted with the advertisement copy).
Here is an example of a cross-join between a table of ad_copy and a table of ad_creative:
You could this query to generate all possible combinations of ad copy and ad creative to help you create more effective ads for Western & Southern. Just be careful: if you had 1,000 rows of ad copy and 1,000 different image creatives, the resulting cross-join would have 1 million rows!
SQL Question 8: Filtering Customer Records
Western & Southern has a customer table which contains customers across the United States. Your task is to filter the customer record to return a list of customers whose last names start with "Johns" and reside in the state of "OH" (Ohio).
Here's some example data for the table:
Example Input:
|customer_id|first_name|last_name|address|city|state|zip_code|
|:----|:----|:----|:----|:----|:----|:----| |8712|Robert|Johnsons|123 Market St.|Cincinnati|OH|45202| |9801|Emily|Johnston|456 Elm St.|Dayton|OH|45405| |4625|Sam|Johnson|789 Pine St.|Columbus|OH|43215| |3346|Mary|John|135 Hill St.|Cleveland|OH|44114| |2953|Jack|Jones|246 River Ave.|Cincinnati|OH|45202|
Example Output:
| customer_id | first_name | last_name | address | city | state | zip_code |
|---|---|---|---|---|---|---|
| 8712 | Robert | Johnsons | 123 Market St. | Cincinnati | OH | 45202 |
| 9801 | Emily | Johnston | 456 Elm St. | Dayton | OH | 45405 |
Answer:
Here is a PostgreSQL query that would solve the problem:
The above SQL query filters the table to return only those records where the last name begins with 'Johns' and the state is 'OH'. The '%' after 'Johns' is a wildcard character that matches any sequence of characters, allowing us to match any last name that begins with 'Johns'. The 'AND' keyword is used to combine the two conditions.
How To Prepare for the Western & Southern 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. Besides solving the earlier Western & Southern SQL interview questions, you should also solve the 200+ SQL exercises on DataLemur which come from companies like Netflix, Google, and Amazon.
Each SQL question has multiple hints, detailed solutions and crucially, there's an interactive coding environment so you can easily right in the browser your SQL query and have it checked.
To prep for the Western & Southern SQL interview you can also be wise to practice interview questions from other insurance companies like:
- W.R. Berkley SQL questions
- Erie Insurance SQL questions
- Cincinnati Fin SQL questions
- Thrivent SQL questions
Explore the latest news and announcements from Western & Southern and stay ahead of the curve in finance!
In case your SQL skills are weak, forget about diving straight into solving questions – strengthen your SQL foundations with this free SQL for Data Analytics course.
This tutorial covers topics including SUM/AVG window functions and sorting data with ORDER BY – both of which show up frequently during Western & Southern interviews.
Western & Southern Financial Group Data Science Interview Tips
What Do Western & Southern Data Science Interviews Cover?
Besides SQL interview questions, the other types of problems tested in the Western & Southern Data Science Interview include:
- AB Testing Questions
- Coding Questions in Python or R
- Business Sense and Product-Sense Questions
- Machine Learning Questions
- Behavioral Interview Questions
How To Prepare for Western & Southern Data Science Interviews?
I think the optimal way to prepare for Western & Southern Data Science interviews is to read the book Ace the Data Science Interview.
It covers 201 interview questions sourced from Facebook, Google, & Amazon. The book's also got a crash course covering Python, SQL & ML. And finally it's vouched for by the data community, which is how it's gotten to be an Amazon best-seller with over 1000+ 5-star reviews.
While the book is more technical, it's also crucial to prepare for the Western & Southern behavioral interview. Start by understanding the company's culture and values.