9 BlackRock SQL Interview Questions (Updated 2024)
Data Analysts and Data Engineers at BlackRock write SQL queries as a core part of their job. They use SQL for analyzing financial data for insights and improving database performance for better decision-making. That's why BlackRock usually asks SQL interview questions.
So, to help you prep, here's 9 BlackRock SQL interview questions – able to answer them all?
9 BlackRock SQL Interview Questions
SQL Question 1: Identify High-Frequency Investment Users at BlackRock
BlackRock is interested in identifying their high-frequency users - these are customers who make a significant number of investments every month. They believe these users are the backbone of their business and want to develop targeted marketing strategies for them.
You are given two tables - and . table includes information about each user - their , , and . table contains information about the investments made by these users - the , , , , and .
Write a SQL query that identifies users who made more than 100 investments in any given month in the last year. Return the user id, total investments for the month, and the month in your result.
Example Input:
| user_id | username | signup_date |
|---|---|---|
| 1 | John88 | 01/15/2015 |
| 2 | JaneDoe | 03/10/2016 |
| 3 | MoneyMaker | 12/12/2017 |
| 4 | InvestQueen | 04/22/2018 |
Example Input:
| investment_id | user_id | investment_date | investment_amount | asset_class |
|---|---|---|---|---|
| 2001 | 1 | 01/01/2021 | 500 | Equity |
| 2005 | 1 | 01/02/2021 | 200 | Bond |
| 2012 | 2 | 01/02/2021 | 1000 | Equity |
| 2045 | 3 | 01/04/2021 | 2500 | Equity |
| 2048 | 2 | 01/05/2021 | 1200 | Equity |
Answer:
This query joins the and tables on . It then groups the results by and month(). It only considers investments made in the last year. The HAVING clause filters out any users who made less than or equal to 100 investments in any given month. The result is ordered by in descending order, so the users with the most investments show up first. We're using PostgreSQL's DATE_PART function to extract the month from the .
To practice a related customer analytics question on DataLemur's free interactive coding environment, try this Microsoft SQL Interview problem:
SQL Question 2: Second Highest Salary
Given a table of BlackRock employee salary information, write a SQL query to find the 2nd highest salary among all employees.
BlackRock Example Input:
| employee_id | salary |
|---|---|
| 1 | 2500 |
| 2 | 800 |
| 3 | 1000 |
| 4 | 1200 |
Example Output:
| second_highest_salary |
|---|
| 1200 |
You can solve this question interactively on DataLemur:
Answer:
You can find a detailed solution here: 2nd Highest Salary.
SQL Question 3: What are database views, and when would you use them?
A database view is a virtual table that is created based on the results of a SELECT statement, and provides you a customized, read-only version of your data that you can query just like a regular table.
Views in SQL can help you enforce data security requirements by hiding sensitive data from certain users, and can improve performance for some queries by pre-computing the results for an intermediate step and storing them in a view (which can be faster than executing the intermediate query each time). However, their read-only nature means that on any underlying update, the view has to be re-computed.
SQL Question 4: Calculate Average Monthly Portfolio Values
Given a dataset containing end of day portfolio values for various funds managed by BlackRock, write a SQL query to calculate the average monthly portfolio value for each fund. Consider only the latest value for each day.
For this problem, we'll use the table:
Example Input:
| value_id | date | fund_id | value |
|---|---|---|---|
| 1001 | 01/05/2022 | F100 | 1200000 |
| 1002 | 01/05/2022 | F105 | 980000 |
| 1003 | 01/06/2022 | F100 | 1250000 |
| 1004 | 01/07/2022 | F105 | 990000 |
| 1005 | 02/05/2022 | F100 | 1300000 |
| 1006 | 02/05/2022 | F105 | 1020000 |
| 1007 | 02/06/2022 | F100 | 1350000 |
| 1008 | 02/06/2022 | F105 | 1050000 |
We want to transform this input into the following output:
Expected Output:
| month | fund_id | avg_value |
|---|---|---|
| 1 | F100 | 1225000 |
| 1 | F105 | 985000 |
| 2 | F100 | 1325000 |
| 2 | F105 | 1035000 |
Answer:
You can achieve this by using PostgreSQL's and functions in combination with :
What this query does is create a subquery that ranks all rows for each fund/fund_id combination by in descending order (so the latest value for each day is ranked first).
Then, the outer query only selects the first ranked row () for each fund/date, calculates the average of these rows per month for each fund with , and groups the results by month and fund_id with . The results are sorted by month and fund_id for ease of reading.
Pro Tip: Window functions are a popular SQL interview topic, so practice all the window function problems on DataLemur
SQL Question 5: What is a foreign key?
A foreign key is a field in a database table that serves as a reference to the primary key of another table, allowing for the creation of a relationship between the two tables.
For a concrete example, let's inspect employee data from BlackRock's HR database:
:
+------------+------------+------------+------------+ | employee_id| first_name | last_name | manager_id | +------------+------------+------------+------------+ | 1 | Aubrey | Graham | 3 | | 2 | Marshal | Mathers | 3 | | 3 | Dwayne | Carter | 4 | | 4 | Shawn | Carter | | +------------+------------+------------+------------+
In this table, is the primary key, and is used to uniquely identify each row.
could be a foreign key. It references the of the manager of each employee in the table, establishing a relationship between the employees and their managers. This foreign key allows you to easily query the table to find out who a specific employee's manager is, or to find out which employees report to a specific manager.
It is possible for a table to have multiple foreign keys that reference primary keys in different tables. For instance, the table could have additional foreign keys for the of the department where an employee works and the of the employee's location.
SQL Question 6: Filtering Client Portfolio Records
BlackRock needs to filter their client portfolio database to identify all clients who are based in the United States, have more than $1,000,000 in their account, and do not hold any bonds. BlackRock also needs to know the total amount of money these clients have in their accounts.
Example Input:
| client_id | country | account_balance | asset_type |
|---|---|---|---|
| 101 | USA | $2,000,000 | Equity |
| 102 | CAN | $1,000,000 | Bond |
| 103 | USA | $1,500,000 | Bond |
| 104 | USA | $3,000,000 | Real Estate |
| 105 | USA | $500,000 | Equity |
Example Output:
| client_id | total_balance |
|---|---|
| 101 | $2,000,000 |
| 104 | $3,000,000 |
Answer:
This query filters the table to include only rows where is 'USA', is greater than 1000000, and is not 'Bond'. It then groups these rows by and calculates the sum of for each group, resulting in a list of client IDs and the total balance of clients that meet the defined conditions.
Look at BlackRock's Technology career page and see what types of roles utilize SQL in their day-to-day.
SQL Question 7: What's the difference between and clause?
The clause serves as a filter for the groups created by the clause, similar to how the clause filters rows. However, is applied to groups rather than individual rows.
For example, say you were a data analyst at BlackRock trying to understand how sales differed by region:
This query retrieves the total sales for all products in each region, and uses the clause to only sales made after January 1, 2023. The rows are then grouped by region and the clause filters the groups to include only those with total sales greater than $400,000.
SQL Question 8: Average Investment Returns
BlackRock is an investment management company. You are given a table where each row represents an account's investments for a particular year, with data on the initial amount of investment, the final amount at the end of the year, and the percentage return. Your task is to find out the average percentage return per year across all investments.
Example Input:
| investment_id | account_id | year | initial_investment | final_investment | perc_return |
|---|---|---|---|---|---|
| 1001 | 201 | 2009 | $10,000 | $10,900 | 9% |
| 1002 | 202 | 2010 | $15,000 | $15,600 | 4% |
| 1003 | 203 | 2011 | $20,000 | $22,000 | 10% |
| 1004 | 204 | 2012 | $18,000 | $20,000 | 11.1% |
| 1005 | 205 | 2013 | $12,000 | $12,500 | 4.2% |
You are expected to write a SQL query to fetch the average percentage return per year.
Answer:
In the query above, we SELECT the year and average percentage return, from the table, grouped by each year, and then ordered by year. This will give us the average percentage return for each year over all investments. The AVG() function is used to calculate the mean of the 'perc_return' column, for each group of rows with the same 'year'. The GROUP BY statement is used to group rows that have the same values in specified columns into aggregated data.
To practice a very similar question try this interactive Wayfair Y-on-Y Growth Rate Question which is similar for calculating year-on-year percentage change or this Amazon Average Review Ratings Question which is similar for calculating average percentage value.
SQL Question 9: Average Investment Returns per Fund Type
As a financial institution, BlackRock offers investment products in the form of several funds. Suppose BlackRock wishes to assess the average returns generated by the different types of investment fund it manages over a specific time period. The following is a SQL interview question that could be posed to achieve this:
Given a database table named containing information about each fund's weekly return, write a SQL query to determine the average return for each fund type for the year 2020. Assume the database table is structured as follows:
Example Input:
| return_id | fund_id | fund_type | week_ending | return_percent |
|---|---|---|---|---|
| 101 | 1001 | Equity | 12/31/2020 | 1.5 |
| 102 | 1002 | Fixed Income | 12/31/2020 | 0.8 |
| 103 | 1001 | Equity | 01/07/2021 | 1.7 |
| 104 | 1003 | Asset Allocation | 12/31/2020 | 2.0 |
| 105 | 1001 | Equity | 01/14/2021 | 1.2 |
Answer:
In the above query, the WHERE clause restricts the data to be considered to the year 2020. The GROUP BY clause then groups this data by , and the AVG function computes the average percentage return for each group.
Expected Output:
| fund_type | avg_return |
|---|---|
| Equity | 1.5 |
| Fixed Income | 0.8 |
| Asset Allocation | 2.0 |
BlackRock SQL Interview Tips
The key to acing a BlackRock SQL interview is to practice, practice, and then practice some more!
In addition to solving the earlier BlackRock SQL interview questions, you should also solve the 200+ SQL questions on DataLemur which come from companies like Facebook, Google and unicorn tech startups.
Each SQL question has multiple hints, fully explained answers along with a discussion board to see how others solved it and most importantly, there's an interactive SQL code editor so you can right online code up your SQL query and have it graded.
To prep for the BlackRock SQL interview it is also a great idea to practice SQL questions from other investment management and private equity companies like:
However, if your SQL query skills are weak, forget about going right into solving questions – strengthen your SQL foundations with this DataLemur SQL tutorial.
This tutorial covers topics including window functions like RANK() and ROW_NUMBER() and cleaning text data – both of these come up often in SQL interviews at BlackRock.
BlackRock Data Science Interview Tips
What Do BlackRock Data Science Interviews Cover?
In addition to SQL interview questions, the other question categories covered in the BlackRock Data Science Interview include:
- Statistics and Probability Questions
- Python Pandas or R Coding Questions
- Product Data Science Interview Questions
- ML Modelling Questions
- Behavioral Based Interview Questions
How To Prepare for BlackRock Data Science Interviews?
I'm sort of biased, but I think the optimal way to prepare for BlackRock Data Science interviews is to read the book Ace the Data Science Interview.
The book has 201 data interview questions sourced from FAANG & startups. It also has a crash course covering Product Analytics, SQL & ML. And finally it's helped thousands of people land their dream job in data, which is why it's earned 1000+ reviews on Amazon and a 4.5-star rating.