9 Jamf SQL Interview Questions (Updated 2024)
At Jamf, SQL is used frequently for conducting comprehensive data analysis to improve software management for Apple devices. That's why Jamf typically asks SQL questions during interviews for Data Science, Data Engineering and Data Analytics jobs.
So, to help you prepare for the Jamf SQL interview, we've curated 9 Jamf SQL interview questions – able to answer them all?
9 Jamf SQL Interview Questions
SQL Question 1: Calculate the monthly average license usage
Jamf is a software company that develops solutions for Apple enterprise management. You're given access to a table with daily product activation data. Your task is to write a query that calculates the average monthly active licenses, per product_id.
Assume the table structure as follows:
Example Input:
| activation_date | product_id | active_licenses |
|---|---|---|
| 01/01/2022 00:00:00 | 1001 | 10 |
| 01/02/2022 00:00:00 | 1001 | 20 |
| 01/03/2022 00:00:00 | 1002 | 15 |
| 02/01/2022 00:00:00 | 1001 | 25 |
| 02/02/2022 00:00:00 | 1002 | 30 |
| 02/03/2022 00:00:00 | 1001 | 35 |
| 03/01/2022 00:00:00 | 1002 | 40 |
| 03/02/2022 00:00:00 | 1001 | 45 |
| 03/03/2022 00:00:00 | 1002 | 50 |
Answer:
In this query, we use a window function to calculate the monthly average. We partition by product_id and use date_trunc to get monthly data. The ORDER BY in the OVER clause will sort the aggregation result by month. Finally, we order the whole result set by month and product_id for readability.
Please note that the date_trunc function is specific to PostgreSQL and some other SQL dialects. It may not be available or may have different syntax in other SQL dialects.
For more window function practice, try this Uber SQL Interview Question on DataLemur's online SQL coding environment:
SQL Question 2: Find the Average Number of Devices Managed Per Employee at Jamf.
As an IT service management company, Jamf manages devices for its clients. The database contains a table and an table. Each device has a unique and is assigned to an employee via an . The table lists each employee's unique .
Given the tables below, determine the average number of devices each employee manages at Jamf.
Answer:
This SQL query will first build a subquery that groups devices by each and counts the number of devices managed by each employee. Then it calculates the of the across all employees. Since employees who are not managing any devices are still listed in the table, they will be taken into account when calculating the average; they will be assumed to have a of 0.
To practice a very similar question try this interactive Amazon Compressed Mean Question which is similar for calculating averages or this Microsoft Teams Power Users Question which is similar for assigning resources to individuals.
SQL Question 3: Can you explain the distinction between a unique and a non-unique index?
While both types of indexes improve the performance of SQL queries by providing a faster way to lookup rows of data, a unique index enforces the uniqueness of the indexed columns while a non-unique index allows duplicate values in the indexed columns.
Suppose you had a table of Jamf employees. Here's an example of a unique index on the column:
This index would ensure that no two Jamf employees have the same , which could be used as a unique identifier for each employee.
Here's a non-unique index example example on the column:
This index would not enforce uniqueness, but it could be used to improve the performance of queries that filter or sort the data based on the column. For example, if you want to quicklly retreive all Data Scientists, the database can use the index to efficiently locate and retrieve the desired records without having to do a full table scan on all Jamf employees.
SQL Question 4: Finding Customers based on Email Domain
As a company providing Apple enterprise management solutions, Jamf stores the details of its customer. Now, Jamf wants to conduct a targeted email campaign for specific domains. Your task is to write a SQL query to find all customers whose email addresses end with "apple.com".
Below are two example tables - one for the input and one for the output.
Example Input:
| customer_id | first_name | last_name | |
|---|---|---|---|
| 1 | John | Doe | johndoe@gmail.com |
| 2 | Jane | Smith | janesmith@apple.com |
| 3 | Bob | Brown | bob.brown@apple.com |
| 4 | Alice | Green | alice.g@jamf.com |
| 5 | Charlie | Black | blackie@hotmail.com |
Example Output:
| customer_id | first_name | last_name | |
|---|---|---|---|
| 2 | Jane | Smith | janesmith@apple.com |
| 3 | Bob | Brown | bob.brown@apple.com |
Answer:
This query uses the keyword in SQL that allows you to search for specific patterns in a column. The '%' sign is used as a wildcard character and will match any sequence of characters. In this query, it is used to find all records where the 'email' field ends with "apple.com".
SQL Question 5: What do stored procedures do?
Stored procedures are a lot like functions in programming. They're used to encapsulate and organize business logic into one unit of code, and they can accept multiple input parameters and return multiple output values.
For a concrete example, suppose you were a Data Scientist on the Marketing Analytics team at Jamf. A task you would encounter freqently would be to calculate the conversion rate for Jamf's ads over a certain time period, for which you would write the following stored procedure:
To use this conversion rate stored procedure, you could call it like this:
SQL Question 6: Find the Total revenue and number of licenses sold to each client
Jim, a Sales executive from Jamf, wants to analyze the revenue from each client and the number of licenses sold to them. He also wishes to analyze this in conjunction with the details about the clients. He has access to the and databases. Can you write a SQL query to provide him with the client name, total revenue, and total number of licenses sold to each client?
Example Input:
| sale_id | client_id | license_id | sale_date | revenue |
|---|---|---|---|---|
| 219 | 248 | 8741 | 07/02/2022 00:00:00 | 1120 |
| 255 | 178 | 9514 | 07/07/2022 00:00:00 | 980 |
| 321 | 248 | 6827 | 07/18/2022 00:00:00 | 1100 |
| 362 | 178 | 9172 | 08/03/2022 00:00:00 | 970 |
| 593 | 159 | 7342 | 06/22/2022 00:00:00 | 1040 |
Example Input:
| client_id | client_name |
|---|---|
| 248 | Apple |
| 178 | Microsoft |
| 159 | Amazon |
Answer:
This query joins the and tables on the field. It then groups the results by the to compute the sum of and count of for each client. The results are then sorted in descending order of .
Example Output:
| client_name | total_revenue | total_licenses_sold |
|---|---|---|
| Apple | 2220 | 2 |
| Microsoft | 1950 | 2 |
| Amazon | 1040 | 1 |
Because join questions come up frequently during SQL interviews, take a stab at this Snapchat JOIN SQL interview question:
SQL Question 7: What is the purpose of the SQL constraint ?
{#Question-7}
A UNIQUE constraint ensures that all values in a column are different. This provides uniqueness for the column(s) and helps identify each row uniquely. Unlike primary key, there can be multiple unique constraints defined per table.
SQL Question 8: Calculating the Optimized Product Pricing Based on Sales
Jamf is a company that sells various tech-related products. Suppose they have performed an extensive pricing experiment and gathered data from the past year. This data includes the product price they set each day, and the quantity of the product sold on that day. Your task involves analyzing this data to find the price that would maximize revenue for each product.
Consider the 'revenue' as a product of 'price' and 'quantity sold'. You have to use SQL math functions and arithmetic operators to derive the ideal price that yields the highest revenue for each product.
To solve this problem, you could first calculate the daily revenue per product, then find the price at which the maximum revenue occurred. This price represents the optimal price.
Here is the sample data:
Example Input:
| date | product_id | price | quantity_sold |
|---|---|---|---|
| 2020-01-01 | 101 | 500 | 20 |
| 2020-01-02 | 101 | 550 | 18 |
| 2020-01-03 | 101 | 600 | 15 |
| 2020-01-04 | 101 | 650 | 12 |
| 2020-01-05 | 101 | 700 | 10 |
| 2020-01-01 | 102 | 800 | 25 |
| 2020-01-02 | 102 | 850 | 22 |
| 2020-01-03 | 102 | 900 | 20 |
| 2020-01-04 | 102 | 950 | 17 |
| 2020-01-05 | 102 | 1000 | 15 |
Expected Output:
| product_id | optimal_price |
|---|---|
| 101 | 500 |
| 102 | 800 |
Answer:
The inner subquery, with window functions, calculates the maximum revenue for each product and assigns a row number based on the date for each (product, revenue) combination. The function ensures that we pick the most recent price if there are multiple prices that achieve the maximum revenue. The outer query selects the price (which is the optimal price) where rn = 1, effectively selecting the row with the maximum revenue for each product.
To practice a very similar question try this interactive Amazon Highest-Grossing Items Question which is similar for calculating maximum revenue per product or this Wayfair Y-on-Y Growth Rate Question which is similar for analyzing sales data over time.
SQL Question 9: Product Activation Over Time
Jamf is a Software-as-a-Service (SaaS) company specializing in enterprise-level Apple device management solutions. Suppose you are a data analyst at Jamf. You have been given a task to extract the monthly count of new product activations for each product. Product activation is when a customer starts using a product after subscribing to it.
Use the table in your query.
Example Input:
| activation_id | customer_id | activation_date | product_id |
|---|---|---|---|
| 101 | 1 | 01/03/2022 00:00:00 | 50001 |
| 102 | 2 | 01/10/2022 00:00:00 | 69852 |
| 103 | 3 | 02/01/2022 00:00:00 | 50001 |
| 104 | 4 | 02/05/2022 00:00:00 | 69852 |
| 105 | 5 | 02/12/2022 00:00:00 | 69852 |
Example Output:
| month | product | activation_count |
|---|---|---|
| 1 | 50001 | 1 |
| 1 | 69852 | 1 |
| 2 | 50001 | 1 |
| 2 | 69852 | 2 |
Answer:
In this question, the key task is to aggregate at multiple levels (product and month) simultaneously. After deriving the month from the using the function, it's standard GROUP BY operations to get the count of unique activations for each product/month combination. Ordering by month and product ensures the final result is presented in a clear, intuitive format.
Jamf SQL Interview Tips
Assuming that you've already got basic SQL skills, the next best tip we have to prepare for the Jamf SQL interview is to solve as many practice SQL interview questions as you can!
Beyond just solving the above Jamf SQL interview questions, you should also solve the 200+ SQL coding questions which come from companies like FAANG tech companies and tech startups.
Each interview question has multiple hints, full answers and most importantly, there's an online SQL coding environment so you can instantly run your query and have it graded.
To prep for the Jamf SQL interview it is also a great idea to solve interview questions from other tech companies like:
In case your SQL query skills are weak, forget about diving straight into solving questions – improve your SQL foundations with this DataLemur SQL tutorial.
This tutorial covers topics including LEAD/LAG window functions and UNION vs. joins – both of which pop up frequently in SQL job interviews at Jamf.
Jamf Data Science Interview Tips
What Do Jamf Data Science Interviews Cover?
Beyond writing SQL queries, the other types of questions tested in the Jamf Data Science Interview are:
- Probability & Stats Questions
- Python or R Programming Questions
- Business Sense and Product-Sense Questions
- ML Modelling Questions
- Behavioral & Resume-Based Questions
How To Prepare for Jamf Data Science Interviews?
To prepare for Jamf Data Science interviews read the book Ace the Data Science Interview because it's got:
- 201 interview questions taken from FAANG & startups
- a crash course covering Stats, ML, & Data Case Studies
- over 900+ reviews on Amazon & 4.5-star rating