SQL Interview Questions for Data Analysts

A Data Analyst who doesn't know SQL is like a solider who can't shoot a gun: utterly useless. Data Analysts are expected to pull and manipulate data from large datasets and generate valuable insights, and the workhorse behind that is usually SQL. That's why most companies, especially competitive big-tech companies like Amazon and Facebook, ask Data Analysts SQL interview questions. So, to help you prepare, scroll down to solve 15 SQL interview questions for Data Analysts!

1. Cards Issued Difference (JPMorgan Chase SQL Interview Question)

Your team at JPMorgan Chase is preparing to launch a new credit card, and to gain some insights, you're analyzing how many credit cards were issued each month.

Write a query that outputs the name of each credit card and the difference in the number of issued cards between the month with the highest issuance cards and the lowest issuance. Arrange the results based on the largest disparity.

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You can solve this JPMorgan Chase SQL problem interactively, and get the full solution explanation.

2. Describe the difference between SQL’s DDL and DML.

Answer: DDL (Data Definition Language) is used to define, modify, and delete database objects such as tables, indexes, and constraints. In contrast, DML (Data Manipulation Language) is used to manipulate the data stored in the database, such as inserting, updating, deleting, and querying data.

3. Compressed Mean (Alibaba SQL Interview Question)

You're trying to find the mean number of items per order on Alibaba, rounded to 1 decimal place using tables which includes information on the count of items in each order ( table) and the corresponding number of orders for each item count ( table).

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There are a total of 500 orders with one item per order, 1000 orders with two items per order, and 800 orders with three items per order.

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Solution:

You can solve this Alibaba SQL problem interactively, and get the full solution explanation.

Enjoyed this one? p.s. here's more Alibaba SQL Interview Questions to practice!

4. What is a primary key and why is it important?

Answer: A primary key is a unique identifier for each record in a database table. It ensures that each row in the table is uniquely identified and allows for efficient data retrieval and indexing.

5. QuickBooks vs TurboTax (Intuit SQL Interview Question)

Intuit provides a range of tax filing products, including TurboTax and QuickBooks, available in various versions.

Write a query to determine the total number of tax filings made using TurboTax and QuickBooks. Each user can file taxes once a year using only one product.

If you find this question interesting, you may also want to try a similar question called Laptop vs Mobile Viewers!

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You can solve this Intuit SQL problem interactively AND see alternate solutions, and get the full solution explanation.

Looking for more Intuit SQL Interview Questions? Check out our Intuit SQL Interview Guide for access to even more questions and solutions!

6. Explain the difference between the INNER JOIN and LEFT JOIN.

Answer: INNER JOIN returns only the rows that have matching values in both tables involved in the join, while LEFT JOIN returns all the rows from the left table and the matched rows from the right table, with NULL values for unmatched rows on the right.

Want to practice SQL JOINS? Try our SQL JOINS Tutorial with Practice Exercises page from our SQL Tutorial guide.

7. Webinar Popularity (Snowflake SQL Interview Question)

As a Data Analyst on Snowflake's Marketing Analytics team, you're analyzing the CRM to determine what percent of marketing touches were of type "webinar" in April 2022. Round your percentage to the nearest integer.

Did you know? Marketing touches, also known as touch points are the brand's (Snowflake's) point of contact with the customers, from start to finish.

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You can solve this Snowflake SQL problem interactively, and get the full solution explanation.

Enjoyed this one? p.s. here's more Snowflake SQL Interview Questions to practice!

8. How do you handle NULL values in SQL queries?

Answer: NULL values in SQL represent missing or unknown data. They can be handled using functions like IS NULL and IS NOT NULL to filter rows with NULL values or using functions like COALESCE or IFNULL to replace NULL values with specified default values.

9. Who Made Quota? (Oracle SQL Interview Question)

As a data analyst on the Oracle Sales Operations team, you are given a list of salespeople’s deals, and the annual quota they need to hit.

Write a query that outputs each employee id and whether they hit the quota or not ('yes' or 'no'). Order the results by employee id in ascending order.

Definitions:

• : Deals acquired by a salesperson in the year. Each salesperson may have more than 1 deal.
• : Total annual quota for each salesperson.

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Solution:

You can solve this Oracle SQL problem interactively, and get the full solution explanation.

Enjoyed this one? p.s. here's more Oracle SQL Interview Questions to practice!

10. Explain the concept of data normalization and its importance.

Answer: Data normalization is the process of organizing data in a database to minimize redundancy and dependency by dividing large tables into smaller tables and defining relationships between them. It ensures data integrity, reduces data duplication, and improves database efficiency.

11. Subject Matter Experts (Accenture SQL Interview Question)

You are tasked with identifying Subject Matter Experts (SMEs) at Accenture based on their work experience in specific domains. An employee qualifies as an SME if they meet either of the following criteria:

1. They have 8 or more years of work experience in a single domain.
2. They have 12 or more years of work experience across two different domains.

Write a query to return the employee IDs of all the subject matter experts at Accenture.

Assumption:

• An employee can only be considered an SME if they meet the experience requirements in either one or two domains. Cases where an employee has experience in more than two domains can be disregarded.

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You can solve this Accenture SQL problem interactively, and get the full solution explanation.

12. Define the term “foreign key” and its significance in database design.

Answer: A foreign key is a column or set of columns in a table that references the primary key or unique key of another table. It establishes a relationship between the two tables, enforcing referential integrity and maintaining consistency in the data.

13. Average Review Ratings (Amazon SQL Interview Question)

Given the reviews table, write a query to retrieve the average star rating for each product, grouped by month. The output should display the month as a numerical value, product ID, and average star rating rounded to two decimal places. Sort the output first by month and then by product ID.

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Solution:

You can solve this Amazon SQL problem interactively, and get the full solution explanation.

Enjoyed this one? p.s. here's more Amazon SQL Interview Questions to practice!

14. What is a stored procedure and how it is different from a function?

Answer: A stored procedure is a precompiled set of SQL statements that are stored in the database and can be executed repeatedly by calling the procedure name. It can contain DML and DDL statements, accept input parameters, and return output values. Unlike functions, stored procedures do not necessarily return a value.

15. Highest Number of Products (eBay SQL Interview Question)

This is the same question as problem #5 in the SQL Chapter of Ace the Data Science Interview!

Assume that you are given the table below-containing information on various orders made by eBay customers. Write a query to obtain the user IDs and number of products purchased by the top 3 customers; these customers must have spent at least $1,000 in total.

Output the user id and number of products in descending order. To break ties (i.e., if 2 customers both bought 10 products), the user who spent more should take precedence.

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Solution:

You can solve this eBay SQL problem interactively, and get the full solution explanation.

Enjoyed this one? p.s. here's more eBay SQL Interview Questions to practice!

SQL Interview Tips

The best way to prepare for the SQL interview is to practice, practice, practice. Besides solving the earlier SQL interview questions, you should also solve the 200+ SQL coding questions which come from companies like FAANG tech companies and tech startups.

Each exercise has hints to guide you, step-by-step solutions and best of all, there is an interactive coding environment so you can right online code up your SQL query and have it checked.

However, if your SQL skills are weak, forget about going right into solving questions – refresh your SQL knowledge with this DataLemur SQL Tutorial.

Data Analyst Interview Tips

To prepare for the Data Analyst interviews read the book Ace the Data Science Interview because it's got:

• 201 Interview Questions from Facebook, Google & startups
• A Crash Course covering Product Analytics, SQL & ML
• Amazing Reviews (900+ 5-star reviews on Amazon)