# 8 Principal Financial SQL Interview Questions (Updated 2024)

Updated on

August 11, 2024

At Principal Financial, SQL is crucial for analyzing financial data trends, including market performance and customer transactions, as well as managing client portfolio databases, such as account information, investment holdings, and risk profiles, which enables data-driven decision making and personalized financial planning. Because of this, Principal Financial often asks SQL questions during interviews for Data Analyst, Data Science, and BI jobs.

So, to help you study for the Principal Financial SQL interview, we've collected 8 Principal Financial SQL interview questions – can you solve them?

## 8 Principal Financial SQL Interview Questions

### SQL Question 1: Identify Power Users at Principal Financial

Principal Financial is a global investment management company, and their customers are people who invest with them. A customer's importance comes from the frequency and amount of their investments. We want to identify power users who are most important to the business.

A power user at Principal Financial is defined as a customer who has made investments more than once in the calendar month, with an overall investment amount for the month greater than \$10,000.

Given the table below, please write a SQL query to identify such power users. Each row in the table signifies one investment transaction.

##### Example Input
investment_idcustomer_idtransaction_dateinvestment_amount
32816506/01/20225000
28918706/02/20224000
17216506/10/20228000
93414206/15/20222000
91246507/01/202210000
71255607/02/20226000
52345607/15/20227000
58944207/25/202215000

This SQL query groups the investments table by month, year, and customer_id. It then counts the number of transactions for each group and also sums up the investment amounts. It then filters out those groups where the transaction count is greater than 1 and the total investment amount is greater than \$10,000. Finally, it orders the resulting groups by year, month and by total investment and transaction count in the descending order.

To practice a super-customer analysis question on DataLemur's free interactive coding environment, try this Microsoft SQL Interview problem:

### SQL Question 2: Top 3 Department Salaries

Suppose there was a table of Principal Financial employee salary data. Write a SQL query to find the top 3 highest earning employees in each department.

#### Principal Financial 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

Try this question interactively on DataLemur:

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: How would you improve the performance of a slow SQL query?

Here's some strategies that can generally speed up a slow SQL query:

• Only query the columns you actually need
• Index the columns used in the query
• Use the right kind of JOIN (be explicit about inner vs. outer joins)
• Use the right data types (for example INT vs BIGINT can save you disk space and memory)

While there's an entire industry dedicated to database performance tuning , for Data Analyst and Data Science interviews at Principal Financial, knowing the above basics should be more than enough to ace the SQL interview! Data Engineers on the other hand should know more about the command and understand a bit more about a query-execution plan.

### SQL Question 4: Calculate Rolling Average of Sales Revenue

Description

Principal Financial provides a variety of financial products and services to individuals and businesses. Including insurance plans, retirement solutions, and investment options.

Assume that you are interviewing for their finance and investment department. You are given a table of their product sales data, and you need to write a SQL query to calculate the 3-month rolling average sales revenue for each product.

##### Example Input:
year_monthproduct_idsales_revenue
20220110011500
20220210011200
20220310011800
20220410012000
20220510012200
20220610012400
20220120012000
20220220011800
20220320012200
20220420012500
20220520012800
20220620013000
##### Example Output:
year_monthproduct_idrolling_avg_revenue
20220310011500
20220410011500
20220510011666.66
20220610012000
20220420012000
20220520012166.66
20220620012500

In this query, Windows Function is used to calculate the 3 months rolling average. This partition is done by , and ordering is based on . It then considers the current row and the 2 preceding rows for calculating the average, providing the 3 months rolling average sales revenue.

For more window function practice, try this Uber SQL Interview Question on DataLemur's interactive SQL code editor:

### SQL Question 5: What is a cross-join, and when would you use one?

A cross-join, also known as a cartesian join, is a JOIN that produces the cross-product of two tables. In a cross-join, each row from the first table is matched with every row from the second table, resulting in a new table with a row for each possible combination of rows from the two input tables.

Suppose you were building a Neural Network ML model, that tried to score the probability of a customer buying a Principal Financial product. Before you started working in Python and Tensorflow, you might want to do some Exploratory Data Analysis (EDA) in SQL, and generate all pairs of customers and Principal Financial products.

Here's a cross-join query you could use to find all the combos:

Cross-joins are great for generating all possible combinations, but they can also create really big tables if you're not careful. For example, if you had 10,000 potential customers, and Principal Financial had 500 different product SKUs, you'd get 5 million rows as a result!!

### SQL Question 6: Click-Through and Conversion Rates for Principal Financial Group

Consider we are working for Principal Financial Group, a global financial investment management leader. To optimize our online services, we often monitor how visitors interact with our web pages. For instance, we look for the click-through rate of our digital banners, and the conversion rate from viewing our financial products to adding a product to the virtual wishlist. Calculate the click-through and conversion rates for our digital banners and financial products.

Given the following tables, write a SQL query that calculates:

1. The click-through rate (CTR) of the digital banners, defined as the number of clicks on the banner divided by the number of views, for each banner.
2. The conversion rate of the financial products, defined as the number of times a product is added to the wishlist divided by the number of times it is viewed, for each product.
##### Example Input:
banner_idbanner_name
1001Summer Investments
1002Retirement Plans
1003New Offers
##### Example Input:
activity_idbanner_idactionactivity_date
80011001view09/10/2022
80021001click09/10/2022
80031002view09/11/2022
80041002view09/11/2022
80051002click09/11/2022
##### Example Input:
product_idproduct_name
2001Mutual Funds
2002Annuity
2003Retirement Account
##### Example Input:
activity_idproduct_idactionactivity_date
90012001view09/11/2022
90032002view09/12/2022
90042002view09/12/2022

This query first calculate the click and view counts for each banner and product in the and common table expressions (CTEs). Then, it joins these CTEs with the and tables to get banner and product names and finally calculates the CTR and Conversion Rate. Note that the count is explicitly cast to to ensure accurate division results.

To practice another question about calculating rates, solve this TikTok SQL question on DataLemur's online SQL coding environment:

### SQL Question 7: What's the purpose of the constraint?

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 Principal Financial's CRM (customer-relationship management) tool.

The FOREIGN KEY constraint ensures that the data in the field of the "opportunities" table is valid, and prevents 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 can be used to ensure that data is not deleted from the accounts table if there are still references to it in the table.

### SQL Question 8: Employees' Adjusted Salary Calculation

Principal Financial maintains a payroll database where each employee's basic salary and bonuses are recorded. The company wants to calculate the adjusted salaries of the employees. Adjusted salary takes into account the taxable portion which is 75% of the basic salary, adds any bonuses and then rounds the amount to the nearest whole number. In addition, it calculates the square root of the annual salary to see their benefits eligibility which applies if the square root is less than 280.

Given two tables and , where has , , and as columns and has , , as columns. Write a PostgreSQL query which outputs , , , , and columns.

##### Table:
emp_idfirst_namelast_name
001JohnDoe
002JaneDoe
003AliceSmith
004BobJohnson
##### Table:
emp_idbasic_salarybonus
001450005000
002390006000
003510004000
004350003000

The query first calculates the taxable portion of the salary and adds any existing bonuses to it then rounds off the final figure providing us with 'adjusted_salary'. We then calculate the square root of the annual adjusted salary to determine 'benefits_eligibility'. The POSTGRESQL function is used to determine the square root and function is used to round off decimals. The result of this calculation is then compared with the value 280 and a CASE statement is used to determine if employees are 'Eligible' or 'Not Eligible' for benefits.

To practice a very similar question try this interactive Alibaba Compressed Mean Question which is similar for involving calculations and rounding results to a certain decimal place or this JPMorgan Chase Cards Issued Difference Question which is similar for < use of aggregate functions to assess financial-related information.

### How To Prepare for the Principal Financial SQL Interview

The best way to prepare for a Principal Financial SQL interview is to practice, practice, practice. Beyond just solving the above Principal Financial SQL interview questions, you should also solve the 200+ DataLemur interview questions which come from companies like Microsoft, Google, Amazon, and tech startups.

Each problem on DataLemur has hints to guide you, full answers and best of all, there's an interactive SQL code editor so you can instantly run your SQL query answer and have it executed.

To prep for the Principal Financial SQL interview you can also be useful to practice SQL questions from other insurance companies like:

Explore the latest news releases from Principal Financial and discover what's driving their growth!

But if your SQL foundations are weak, don't worry about jumping right into solving questions – improve your SQL foundations with this free SQL for Data Analytics course.

This tutorial covers SQL concepts such as rank window functions and filtering strings based on patterns – both of these pop up often in SQL interviews at Principal Financial.

### Principal Financial Data Science Interview Tips

#### What Do Principal Financial Data Science Interviews Cover?

In addition to SQL interview questions, the other topics covered in the Principal Financial Data Science Interview include:

#### How To Prepare for Principal Financial Data Science Interviews?

To prepare for the Principal Financial Data Science interview make sure you have a deep understanding of the company's values and mission – this will be clutch for acing the behavioral interview. For technical interviews get ready by reading Ace the Data Science Interview. The book's got:

• 201 Interview Questions from Google, Microsoft & tech startups
• A Crash Course covering Python, SQL & ML
• Great Reviews (1000+ 5-star reviews on Amazon)