9 Vertex Pharmaceuticals SQL Interview Questions (Updated 2024)
Data Analytics, Data Science, and Data Engineering employees at Vertex Pharmaceuticals rely on SQL to analyze complex genome sequencing data, helping them uncover insights that drive innovative drug development. They also use SQL to manage clinical trial data, ensuring that every step of the research process is efficient and effective, this is the reason why Vertex Pharmaceuticals evaluates jobseekers on SQL coding interview questions.
So, to help prep you for the Vertex Pharmaceuticals SQL interview, here’s 9 Vertex Pharmaceuticals SQL interview questions – scroll down to start solving them!
9 Vertex Pharmaceuticals SQL Interview Questions
SQL Question 1: Calculate the Average dosage of Medicine per Drug Family
As a data analyst at Vertex Pharmaceuticals, imagine you are working with a data set containing information about different drugs, their families and the dosage prescribed to patients. You are asked to calculate the average dosage of medicine per drug family over each quarter of a year.
The table logs each prescription medication given to a patient. All dosages are measured in the same units (say, milligrams), regardless of the actual medicine:
Example Input:
| prescription_id | patient_id | prescription_date | drug_id | dosage |
|---|---|---|---|---|
| 5891 | A1289 | 2022-02-13 00:00:00 | 3001 | 250 |
| 9928 | B8930 | 2022-01-11 00:00:00 | 5001 | 500 |
| 8274 | C1123 | 2022-05-17 00:00:00 | 2001 | 100 |
| 6190 | C1123 | 2022-05-20 00:00:00 | 5001 | 300 |
| 7827 | A7732 | 2022-04-04 00:00:00 | 2001 | 200 |
The table contains information about each drug including its associated drug family:
Example Input:
| drug_id | drug_name | drug_family |
|---|---|---|
| 3001 | Drug A | Family 1 |
| 5001 | Drug B | Family 2 |
| 2001 | Drug C | Family 2 |
You can use window functions along with grouping to solve this problem.
Answer:
The SQL window function provided calculates the average dosage of different drug families for each quarter of a year. The clause in the function is used to partition the data by drug family and quarter of prescription date, while the function gives an average of the dosage for each subset.
Once the required join is performed between the two input tables, the relevant fields are selected for final output; namely the drug's family, the quarter of the year the drug was prescribed, and the average dosage of the drug in that quarter. These are then grouped properly and presented in a readable and meaningful way.
Pro Tip: Window functions are a frequent SQL interview topic, so practice all the window function problems on DataLemur
SQL Question 2: Top Department Salaries
Given a table of Vertex Pharmaceuticals employee salaries, write a SQL query to find the top three highest paid employees within each department.
Vertex Pharmaceuticals 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 |
Code your solution to this question interactively 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 code above is tough, you can find a detailed solution with hints here: Top 3 Department Salaries.
SQL Question 3: In database design, what do foreign keys do?
A foreign key is a field in a database table that links to the primary key of another table, establishing a connection between the two tables. For example, let's analyze Vertex Pharmaceuticals' Google Ads campaigns data:
:
| ad_id | campaign_id | keyword | click_count |
|---|---|---|---|
| 1 | 201 | Vertex Pharmaceuticals reviews | 120 |
| 2 | 202 | Vertex Pharmaceuticals pricing | 150 |
| 3 | 101 | buy Vertex Pharmaceuticals | 65 |
| 4 | 101 | Vertex Pharmaceuticals alternatives | 135 |
is a foreign key that connects to the of the corresponding Google Ads campaign. This establishes a relationship between the ads and their campaigns, enabling easy querying to find which ads belong to a specific campaign or which campaigns a specific ad belongs to.
The table may also have multiple foreign keys that reference primary keys in other tables. For example, and foreign keys could be used to link each ad to its ad group and the Google Ads account that the campaigns belong to, respectively.
SQL Question 4: Filtering Patient Data Based on Multiple Conditions
Suppose you are given a dataset containing patient records. Each record includes the patient's ID, age, diagnosis date, the therapeutic area of their treatment, and whether they are part of a clinical trial. Write an SQL query to select the patients that are aged above 60, have been diagnosed after the 1st of January, 2021, and are not part of any clinical trials.
Example Input:
| patient_id | age | diagnosis_date | therapeutic_area | in_trial |
|---|---|---|---|---|
| 1123 | 64 | 06/10/2021 | "Oncology" | False |
| 1167 | 45 | 08/15/2020 | "Neurology" | True |
| 1295 | 72 | 02/02/2021 | "Oncology" | False |
| 1342 | 67 | 01/20/2020 | "Diabetes" | False |
| 1490 | 55 | 07/25/2021 | "Neurology" | True |
Example Output:
| patient_id | age | diagnosis_date | therapeutic_area |
|---|---|---|---|
| 1123 | 64 | 06/10/2021 | "Oncology" |
| 1295 | 72 | 02/02/2021 | "Oncology" |
Answer:
This SQL block filters the patient records based on the described conditions: greater than 60, after the 1st of January, 2021, and not in any clinical trials. The output only includes the columns we are interested in: , , , and .
SQL Question 5: Why would you use the SQL constraint?
The CHEK constraint is used to enforce rules on the data in a specific column. If a row is inserted or updated with data that does not follow the constraint's rule, the operation will fail.
For example, say you had a database that stores ad campaign data from Vertex Pharmaceuticals's Google Analytics account.
Here's what some constraints could look like:
In this example, the constraint is used to ensure that the and fields have positive values. This helps to ensure that the data in the database is valid and makes sense in the context of ad campaigns.
You can also use the constraint to ensure that data meets other specific conditions. For example, you could use a constraint to ensure that the is before the for each ad campaign.
SQL Question 6: Average dosage quantity of medicine for patients
As part of the 'Vertex Pharmaceuticals' data team, you were tasked to find the average dosage quantity prescribed to patients for each medicine. Among the various data tables provided, you have the table that stores the dosage prescribed for each patient for a particular medicine.
The table is structured in the following way:
:
| prescription_id | patient_id | medicine_id | dosage_quantity |
|---|---|---|---|
| 101 | 121 | 001 | 50 |
| 102 | 122 | 002 | 75 |
| 103 | 123 | 001 | 60 |
| 104 | 124 | 003 | 30 |
| 105 | 125 | 001 | 90 |
| 106 | 126 | 002 | 80 |
Question: Write a SQL query that can find the average dosage quantity prescribed for each medicine from the table.
Answer:
This query groups all rows by the , and then calculates the average of the for each group(i.e., each medicine). The function is used to calculate average values for each group partitioned by the clause.
To practice a very similar question try this interactive CVS Health Pharmacy Analytics (Part 1) Question which is similar for calculating metrics related to medicine or this Amazon Average Review Ratings Question which is similar for breaking down a dataset to find averages.
SQL Question 7: How do you determine which records in one table are not present in a second table?
To discover records in one table that are not present in another, you can utilize a and filter out any values in the right-side table.
For example, say you had a table of Vertex Pharmaceuticals customers and a 2nd table of all purchases made with Vertex Pharmaceuticals. To find all customers who did not make a purchase, you'd use the following
This query fetches all rows from the customers table, along with any rows that match in the purchases table. If there is no matching row in the purchases table, values will be returned for all of the right table's columns. The clause then filters out any rows where the purchases.id column is NULL, leaving only customers who have not made a purchase.
SQL Question 8: Find Customers Using Specific Drugs
You have been given a table named "customer_records" that contains data about the customers of Vertex Pharmaceuticals. Your task is to write a SQL query to find all customers who are using a medication with a name that starts with the letter 'T'.
Here is a sample of how the "customer_records" table could look like:
Example Input:
| customer_id | customer_name | medicine_name |
|---|---|---|
| CR01 | John Doe | Telaprevir |
| CR02 | Jane Doe | Lumacaftor |
| CR03 | David Smith | Tobramycin |
| CR04 | Emma Johnson | Orkambi |
| CR05 | Michael Brown | Trikafta |
You are to find:
Example Output:
| customer_id | customer_name | medicine_name |
|---|---|---|
| CR01 | John Doe | Telaprevir |
| CR03 | David Smith | Tobramycin |
| CR05 | Michael Brown | Trikafta |
Answer:
In PostgreSQL, the query would look like this:
This query selects all records from the table where the field starts with 'T'. The symbol is a wildcard that matches any sequence of characters. The keyword is used in a clause to search for a specified pattern in a column.
SQL Question 9: Analyzing Customer and Drug Data
As a data analyst for Vertex Pharmaceuticals, you are tasked with evaluating customer purchase history for each drug to identify trends and analyze drug performance. The company has two tables and . The table has columns , , , (date of birth), , , and . The table has columns , , , , and .
Write a SQL query to fetch the total quantity and total cost of each drug purchased by each customer. Arrange your results by and .
Example Input:
| cust_id | first_name | last_name | dob | address | city | state | zip_code |
|---|---|---|---|---|---|---|---|
| 101 | John | Doe | 1980-01-01 | 123 Elm Street | Cambridge | MA | 12345 |
| 102 | Jane | Smith | 1975-02-02 | 456 Oak Drive | Boston | MA | 67890 |
| 103 | Jill | Johnson | 1990-03-03 | 789 Pine Lane | Somerville | MA | 13579 |
Example Input:
| purchase_id | cust_id | drug_id | purchase_date | quantity | total_cost |
|---|---|---|---|---|---|
| 201 | 101 | D001 | 2022-01-01 | 30 | 150 |
| 202 | 101 | D001 | 2022-02-01 | 20 | 100 |
| 203 | 102 | D002 | 2022-03-01 | 10 | 200 |
| 204 | 102 | D001 | 2022-04-01 | 15 | 75 |
| 205 | 103 | D003 | 2022-05-01 | 25 | 250 |
Answer:
This query uses an to combine the customers and purchases tables based on matching values. We then group the results by and in order to calculate the total quantity and cost per drug for each customer. The ORDER BY statement then arranges the results in order of and .
Because joins come up frequently during SQL interviews, practice this Spotify JOIN SQL question:
Vertex Pharmaceuticals SQL Interview Tips
The key to acing a Vertex Pharmaceuticals SQL interview is to practice, practice, and then practice some more! Beyond just solving the earlier Vertex Pharmaceuticals SQL interview questions, you should also solve the 200+ SQL questions from real Data Science & Analytics interviews which come from companies like FAANG (FB, Apple, Amazon, Netflix, Google).
Each exercise has multiple hints, step-by-step solutions and crucially, there's an online SQL code editor so you can easily right in the browser your SQL query and have it checked.
To prep for the Vertex Pharmaceuticals SQL interview it is also a great idea to practice SQL questions from other healthcare and pharmaceutical companies like:
- Zoetis SQL questions
- Zimmer Biomet Holdings SQL questions
- Owens & Minor SQL questions
- Quest Diagnostics SQL questions
However, if your SQL foundations are weak, don't worry about diving straight into solving questions – go learn SQL with this SQL tutorial for Data Analytics.
This tutorial covers things like transforming strings with CONCAT()/LOWER()/TRIM() and LEAD window function – both of these show up frequently during Vertex Pharmaceuticals SQL assessments.
Vertex Pharmaceuticals Data Science Interview Tips
What Do Vertex Pharmaceuticals Data Science Interviews Cover?
In addition to SQL query questions, the other types of problems to practice for the Vertex Pharmaceuticals Data Science Interview include:
- AB Testing Questions
- Python Pandas or R Coding Questions
- Business Sense and Product-Sense Questions
- Machine Learning Questions
- Behavioral Based Interview Questions
How To Prepare for Vertex Pharmaceuticals Data Science Interviews?
To prepare for the Vertex Pharmaceuticals Data Science interview make sure you have a deep understanding of the company's culture and values – this will be important for acing the behavioral interview. For the technical Data Science interviews, get ready by reading Ace the Data Science Interview. The book's got:
- 201 Interview Questions from Facebook, Google & startups
- A Refresher covering Python, SQL & ML
- Amazing Reviews (1000+ reviews, 4.5-star rating)