8 Paychex SQL Interview Questions (Updated 2024)
Data Science, Data Engineering and Data Analytics employees at Paychex use SQL for analyzing large datasets to uncover trends in employee compensation and benefits, as well as managing client data in the human resources management system to ensure accurate and timely payroll processing. For this reason, Paychex asksSQL questions during job interviews.
So, to help you prep, here's 8 Paychex SQL interview questions – able to solve them?
8 Paychex SQL Interview Questions
SQL Question 1: Calculate Payroll History for Employees
Given a dataset of employee earnings, can you write a SQL query to calculate the total payroll for each quarter for the past year? In other words, your answer should find the payroll total per quarter for each department in the company.
Please base your answer on the following table structure:
Example Input:
| id | dept_id | employee_id | pay_date | amount |
|---|---|---|---|---|
| 1 | 2 | 1000 | 2021/01/30 | 1000.00 |
| 2 | 2 | 1001 | 2021/02/27 | 2000.00 |
| 3 | 1 | 1002 | 2021/03/30 | 1500.00 |
| 4 | 1 | 1003 | 2021/05/30 | 2500.00 |
| 5 | 2 | 1000 | 2021/04/30 | 1200.00 |
Where:
- : unique identifier for each payment.
- : department identifier where the employee works.
- : identifier for each employee.
- : the date when the payroll was processed.
- : the net amount processed in the payroll.
Answer:
This SQL query calculates the total payroll for every department () for each quarter of the past year. The function is used to get the quarter and year from the . The function adds up all the per quarter per department. The clause filters only the earnings from the past year. The output is ordered by year and quarter in descending order, and department in ascending order.
Pro Tip: Window functions are a frequent SQL interview topic, so practice every window function problem on DataLemur
SQL Question 2: Second Highest Salary
Assume there was a table of Paychex employee salary data. Write a SQL query to find the 2nd highest salary at the company.
Paychex Example Input:
| employee_id | salary |
|---|---|
| 1 | 2500 |
| 2 | 800 |
| 3 | 1000 |
| 4 | 1200 |
Example Output:
| second_highest_salary |
|---|
| 1200 |
Solve this question directly within the browser on DataLemur:
Answer:
You can find a step-by-step solution here: 2nd Highest Salary.
SQL Question 3: What distinguishes an inner join from a full outer join?
An inner join only includes rows from both tables that satisfy the join condition, whereas a full outer join includes all rows from both tables, regardless of whether they match the join condition or not.
For a concrete example, imagine you had two database tables, an advertising campaigns table which had information on Google Ads keywords and how much was bid for each keyword, and a Paychex sales table, which has data on how many products were sold and which Google Ads keyword drove that sale.
: retrieves rows from both tables where there is a match in the shared key or keys. For example, an INNER JOIN between the table and the table could be performed using the keyword column as the shared key. This would retrieve only the rows where the keyword in the table matches the keyword in the table.
: retrieves all rows from both tables, regardless of whether there is a match in the shared key or keys. If there is no match, values will be returned for the columns of the non-matching table.
SQL Question 4: Payroll Processing of Paychex
Paychex is a company that provides payroll, human resource, and benefits outsourcing services for small- to medium-sized businesses.
Consider you have two tables: and . The table stores the details of each employee in the company. The table stores the payroll data for each month.
Table Structure are as follows:
:
| employee_id | first_name | last_name | hire_date | department |
|---|---|---|---|---|
| E101 | John | Doe | 02/01/2002 | HR |
| E102 | Jane | Smith | 05/03/2001 | SALES |
| E103 | Tom | Brown | 11/07/2003 | IT |
:
| payroll_id | employee_id | month_year | base_salary | bonus |
|---|---|---|---|---|
| P101 | E101 | 01/2022 | $5000 | $500 |
| P102 | E102 | 01/2022 | $5500 | $250 |
| P103 | E103 | 01/2022 | $4200 | $0 |
Write a SQL query to obtain the total salary (base salary + bonus) paid to employees in a given department for a specific month. Let's take department and month as an example.
Answer:
Here is the SQL code that would solve the problem.
This query performs a join operation on and tables using the as a key to combine the data. The WHERE clause filters the records for department and month . The SUM function is used in conjunction with GROUP BY to get the total salary for the specified department and month.
SQL Question 5: What's the main difference between the 'BETWEEN' and 'IN' operators in SQL?
The operator is used to select rows that fall within a certain range of values, while the operator is used to select rows that match values in a specified list.
For example, suppose you are a data analyst at Paychex and have a table of advertising campaign data. To find campaigns with a spend between 5k, you could use BETWEEN:
To find advertising campaigns that were video and image based (as opposed to text or billboard ads), you could use the operator:
SQL Question 6: Calculate the Average Salary Paid by Paychex Clients
A Paychex Client is a company that uses Paychex payroll services. You are given a database table which records the salaries paid to employees by Paychex Clients. Your task is to write a SQL query that can calculate the average salary paid by each client for the years 2021 and 2022.
Input:
| pay_id | client_id | year | employee_id | salary |
|---|---|---|---|---|
| 8237 | 200 | 2021 | 7625 | $70,000 |
| 1782 | 150 | 2021 | 5429 | $80,000 |
| 2529 | 350 | 2021 | 9251 | $105,000 |
| 3572 | 200 | 2022 | 8756 | $85,000 |
| 4371 | 150 | 2022 | 6392 | $92,000 |
| 5623 | 350 | 2022 | 10489 | $110,000 |
Expected Output:
| client_id | year | avg_salary |
|---|---|---|
| 150 | 2021 | $80,000 |
| 150 | 2022 | $92,000 |
| 200 | 2021 | $70,000 |
| 200 | 2022 | $85,000 |
| 350 | 2021 | $105,000 |
| 350 | 2022 | $110,000 |
Answer:
This query groups the data from the table by and . The function is used inside the statement to calculate the average salary for each client for the specified years. Finally, the results are ordered by and .
To practice a very similar question try this interactive Wayfair Y-on-Y Growth Rate Question which is similar for calculating year-on-year changes or this Amazon Average Review Ratings Question which is similar for calculating averages within a group.
SQL Question 7: What does it mean to perform a self-join?
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.
For example, say you had website visitor data for Paychex, exported from the company's Google Analytics account. In support of the web-dev team, you had to analyze pairs of pages for UX or navigational issues. As part of that analysis, you wanted to generate all pairs of URLs, but needed to avoid pairs where both the URLs were the same since that's not a valid pair.
The self-join query would like the following:
This query returns the url of each page () along with the url of the page that referred to it (). The self-join is performed using the field, which specifies the id of the page that referred the visitor to the current page, and avoids any pages that referred themself (aka data anomalies).
SQL Question 8: Finding Clients From Specific States
As a Paychex employee, you have access to a customer records database. Your task is to filter out and list the client data for clients from New York ("NY") and California ("CA").
You have a table with the following structure:
Example Input:
| client_id | name | signup_date | service_plan | state |
|---|---|---|---|---|
| 1001 | Company A | 01/15/2019 | Basic | NY |
| 1002 | Company B | 04/27/2020 | Premium | CA |
| 1003 | Company C | 08/12/2018 | Advanced | OH |
| 1004 | Company D | 06/04/2020 | Basic | CA |
| 1005 | Company E | 09/30/2019 | Basic | MI |
Your task is to write a SQL query that returns clients located in NY and CA. The query should display the , , , and for these clients.
Answer:
The PostgreSQL query you need is shown below:
This query selects the , , and from the table where the is either 'NY' or 'CA'. The LIKE operator in PostgreSQL is used to match text values against a pattern, and the 'NY' and 'CA' are the specific patterns we are looking for.
How To Prepare for the Paychex SQL Interview
The best way to prepare for a Paychex SQL interview is to practice, practice, practice. Besides solving the above Paychex SQL interview questions, you should also solve the 200+ SQL Interview Questions on DataLemur which come from companies like Google, Facebook, Microsoft and Amazon.
Each interview question has multiple hints, detailed solutions and crucially, there is an interactive coding environment so you can right online code up your query and have it executed.
To prep for the Paychex SQL interview it is also a great idea to practice SQL questions from other financial services companies like:
Explore the latest happenings at Paychex and discover how they're helping businesses thrive!
In case your SQL coding skills are weak, forget about going right into solving questions – refresh your SQL knowledge with this free SQL for Data Analytics course.
This tutorial covers topics including CASE/WHEN statements and Subquery vs. CTE – both of these come up frequently in Paychex SQL assessments.
Paychex Data Science Interview Tips
What Do Paychex Data Science Interviews Cover?
Beyond writing SQL queries, the other topics to prepare for the Paychex Data Science Interview are:
- Probability & Statistics Questions
- Python or R Coding Questions
- Product Analytics Questions
- ML Modelling Questions
- Behavioral Interview Questions centered on Paychex values & principles
How To Prepare for Paychex Data Science Interviews?
To prepare for Paychex Data Science interviews read the book Ace the Data Science Interview because it's got:
- 201 interview questions sourced from companies like Google, Tesla, & Goldman Sachs
- a crash course covering Stats, ML, & Data Case Studies
- over 1000+ reviews on Amazon & 4.5-star rating
Also focus on the behavioral interview – prepare for that with this list of common Data Scientist behavioral interview questions.