10 Sapiens SQL Interview Questions (Updated 2024)
Sapiens employees write SQL queries daily for analyzing insurance-related data to extract insights and for managing, organizing and querying complex databases to support decision-making processes. That's why Sapiens often tests SQL questions in interviews for Data Science and Data Engineering positions.
As such, to help you prepare for the Sapiens SQL interview, we've curated 10 Sapiens SQL interview questions can you solve them?
10 Sapiens SQL Interview Questions
SQL Question 1: Analyzing Monthly Average Product rating
Sapiens is a technology company that produces various software and hardware products. Assume that they use a simple system where their users can post reviews and ratings for their products. The review table schema is as follows:
| Column | Type |
|---|---|
| review_id | Integer |
| user_id | Integer |
| submit_date | Datestamp |
| product_id | Integer |
| stars | Integer (1-5) |
Given the table, write a SQL query that calculates the average product rating on a monthly basis for each product.
Here is some sample input data:
Example Input:
| review_id | user_id | submit_date | product_id | stars |
|---|---|---|---|---|
| 6171 | 123 | 2022-06-08 | 50001 | 4 |
| 7802 | 265 | 2022-06-10 | 69852 | 4 |
| 5293 | 362 | 2022-06-18 | 50001 | 3 |
| 6352 | 192 | 2022-07-26 | 69852 | 3 |
| 4517 | 981 | 2022-07-05 | 69852 | 2 |
The output should return each month, each product and average stars in that month.
Example Output:
| month | product_id | avg_stars |
|---|---|---|
| 6 | 50001 | 3.5 |
| 6 | 69852 | 4.0 |
| 7 | 69852 | 2.5 |
Answer:
In PostgreSQL, you can use the function to get the month from the . You can then group by the month and to calculate the average .
This query works by first extracting the month from the using the function. The function then calculates the average for each month-product combination. The clause groups the data by month and , and the clause orders the result by month and .
p.s. Window functions show up pretty frequently during SQL interviews, so practice the 27+ window function questions on DataLemur
SQL Question 2: Top 3 Salaries
Assume there was a table of Sapiens employee salary data. Write a SQL query to find the top three highest paid employees within each department.
Sapiens Example Input:
| employee_id | name | salary | department_id |
|---|---|---|---|
| 1 | Emma Thompson | 3800 | 1 |
| 2 | Daniel Rodriguez | 2230 | 1 |
| 3 | Olivia Smith | 2000 | 1 |
| 4 | Noah Johnson | 6800 | 2 |
| 5 | Sophia Martinez | 1750 | 1 |
| 8 | William Davis | 6800 | 2 |
| 10 | James Anderson | 4000 | 1 |
Example Input:
| department_id | department_name |
|---|---|
| 1 | Data Analytics |
| 2 | Data Science |
Example Output:
| department_name | name | salary |
|---|---|---|
| Data Analytics | James Anderson | 4000 |
| Data Analytics | Emma Thompson | 3800 |
| Data Analytics | Daniel Rodriguez | 2230 |
| Data Science | Noah Johnson | 6800 |
| Data Science | William Davis | 6800 |
You can solve this problem directly within the browser on DataLemur:
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 solution above is hard to understand, you can find a detailed solution here: Top 3 Department Salaries.
SQL Question 3: What are the various forms of normalization?
Normalization is the process of organizing fields and tables of a database to minimize redundancy and dependency. While there are technically 5 levels (normal forms), the 3 most important normal forms you need to know about for SQL interviews at Sapiens are:
- First Normal Form (1NF): This should fix remove a table's duplicate columns. Also, each column should contain only a single value (no lists or containers of data), and finally each row of table should have a unique identifier as well.
- Second Normal Form (2NF): A table is in its second normal form if it meets all requirements of the first normal form and places the subsets of columns in separate tables. The relationships between tables are created using primary/foreign keys.
- Third Normal Form (3NF): The table should be in the second normal form. There should be no dependency on another non-key attribute (meaning a primary key should be the only thing required to identify the row).
SQL Question 4: Designing a Lead Management System
Sapiens is planning to create a Lead Management System where they can keep track of the potential customers who are interested in their products. The system will track various information about each lead including names, contact information, the product they are interested in, the stage of the lead (e.g., contacted, proposal sent, etc.), and the date when the lead was generated.
Given the information below, model the necessary tables to capture this information. Further, write a SQL query to produce a report that shows, for each product, how many leads are in each stage.
Example Input:
Example Input:
Answer:
This SQL query will join the table and the table on . It will then group the results by and , and count the number of values for each group. Therefore, it will provide the number of leads in each stage for each product.
SQL Question 5: Can you explain the concept of a constraint in SQL?
SQL constraints are used to specify rules for the data in a table. They can be applied to single or multiple fields in a table when the table is created, or after the table has been created using the ALTER TABLE command.
For example, say you had a database that stores ad campaign data from Sapiens's Google Analytics account.
Here's what some constraints could look like:
SQL Question 6: Filter Customers based on Subscription Status and Last Purchase Date
For Sapiens, an educational software company, you are provided with a list of customers, their subscription status, and last purchase date. As part of the company's customer retention program, they are interested in identifying customers who have an active subscription but haven't made a purchase in the last 90 days for targeted marketing campaigns.
Write a SQL query to filter out these specific customers from the given list.
Example Input:
| customer_id | subscription_status | last_purchase_date |
|---|---|---|
| 1234 | Active | 2022-04-19 |
| 5678 | Inactive | 2022-03-10 |
| 9012 | Active | 2022-08-01 |
| 3456 | Active | 2022-05-05 |
| 7890 | Inactive | 2022-07-22 |
Example Output:
| customer_id | subscription_status | last_purchase_date |
|---|---|---|
| 1234 | Active | 2022-04-19 |
| 3456 | Active | 2022-05-05 |
Answer:
This query filters out the customers who have an 'Active' subscription status and whose last purchase was made more than 90 days ago from the current date. The 'INTERVAL' keyword is used in PostgreSQL to represent a time period.
SQL Question 7: How can you select records without duplicates from a table?
The keyword added to a statement can be used to get records without duplicates.
For example, say you had a table of Sapiens customers:
| name | city |
|---|---|
| Akash | SF |
| Brittany | NYC |
| Carlos | NYC |
| Diego | Seattle |
| Eva | SF |
| Faye | Seattle |
Suppose you wanted to figure out which cities the customers lived in, but didn't want duplicate results, you could write a query like this:
Your result would be:
| city |
|---|
| SF |
| NYC |
| Seattle |
SQL Question 8: Average Project Duration
As a data analyst at Sapiens, a software consulting company, you are asked to assess the average duration in days of all their completed software development projects in the year 2022. The projects are logged in a table that contains , , , and .
Example Input:
| project_id | start_date | end_date | client_id |
|---|---|---|---|
| 1 | 2022-01-05 | 2022-01-30 | 5 |
| 2 | 2022-02-10 | 2022-03-20 | 7 |
| 3 | 2022-02-15 | 2022-03-01 | 10 |
| 4 | 2022-04-01 | 2022-05-15 | 3 |
| 5 | 2022-05-20 | 2022-06-15 | 5 |
Expected Output:
| Average_Duration |
|---|
| 40 |
Answer:
The PostgreSQL query to find the solution is:
In the SQL query above, the function is used to calculate the duration of each project in days. The function then calculates the average duration of all the projects. The condition is included to keep only projects that took place in the year 2022.
To practice a very similar question try this interactive Facebook Average Post Hiatus (Part 1) Question which is similar for handling date differences or this Amazon Server Utilization Time Question which is similar for calculating durations.
SQL Question 9: Find Employee Information
Sapiens is a company with several employees. The company maintains a database of their employees. You are tasked to find all employees who work in the 'IT' department and their names start with a specific letter. Let's assume 'A'.
Example Input:
| employee_id | first_name | last_name | department | hire_date |
|---|---|---|---|---|
| 101 | Adam | Smith | IT | 01/14/2020 |
| 102 | Albert | Brown | IT | 05/16/2021 |
| 103 | Ana | Roberts | Marketing | 06/22/2021 |
| 104 | Amar | Sandhu | Sales | 08/27/2020 |
| 105 | Astrid | Larsen | IT | 09/12/2019 |
Here, we need to find employees who work in 'IT' and whose first name start with 'A'.
Answer:
This query uses the operator to search for employees in the 'IT' department whose names start with a specified letter, here 'A'. The '%' is a wildcard character in SQL that matches any sequence of characters, so 'A%' matches any string that starts with 'A'. As a result, the query will retrieve the records of all employees in the 'IT' department whose first names start with 'A'.
Example Output:
| employee_id | first_name | last_name | department | hire_date |
|---|---|---|---|---|
| 101 | Adam | Smith | IT | 01/14/2020 |
| 102 | Albert | Brown | IT | 05/16/2021 |
| 105 | Astrid | Larsen | IT | 09/12/2019 |
SQL Question 10: In SQL, Are NULL values the same as a zero or blank space?
{#Question-10}
In SQL, a value is NOT the same as a zero or a blank space. A NULL value represents the absence of a value or a missing value, whereas both zero and blank space are actually values.
To handle nulls, the function is often used to check for a null, and if there is a null, you can assign a default value.
Sapiens SQL Interview Tips
The best way to prepare for a Sapiens SQL interview is to practice, practice, practice.
In addition to solving the above Sapiens SQL interview questions, you should also solve the 200+ SQL exercises on DataLemur which come from companies like Netflix, Airbnb, and Amazon.
Each SQL question has hints to guide you, step-by-step solutions and best of all, there's an online SQL coding environment so you can right in the browser run your SQL query and have it executed.
To prep for the Sapiens SQL interview it is also helpful to practice SQL questions from other tech companies like:
But if your SQL coding skills are weak, forget about diving straight into solving questions – go learn SQL with this interactive SQL tutorial.
This tutorial covers SQL concepts such as handling timestamps and inner vs. outer JOIN – both of which show up frequently in SQL interviews at Sapiens.
Sapiens Data Science Interview Tips
What Do Sapiens Data Science Interviews Cover?
Besides SQL interview questions, the other types of questions to practice for the Sapiens Data Science Interview include:
- Experimental Design & AB Testing Questions
- Coding Questions in Python or R
- Product Data Science Interview Questions
- Machine Learning and Predictive Modeling Questions
- Behavioral & Resume-Based Questions
How To Prepare for Sapiens Data Science Interviews?
I'm sorta biased, but I believe the optimal way to prepare for Sapiens Data Science interviews is to read the book Ace the Data Science Interview.
The book covers 201 data interview questions taken from FAANG (FB, Apple, Amazon, Netflix, Google). It also has a refresher on SQL, AB Testing & ML. And finally it's helped thousands of people land their dream job in data, which is why it's got over 1000+ 5-star reviews on Amazon.