Practice SQL interview Questions for Data Science

Course Description: In this comprehensive course, you will learn and practice SQL interview questions tailored specifically for Data Science roles. The course is designed to cover essential SQL topics and equip you with the skills needed to excel in your SQL-related interviews.

Course Topics:

1. SQL Basics and Syntax:

   • Understand the fundamental SQL commands and syntax required for querying databases.

   • Practice writing SELECT, FROM, WHERE, and ORDER BY clauses.

   • Mastering joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN) and subqueries.

2. Data Manipulation and DDL:

   • Learn how to manipulate data in SQL using INSERT, UPDATE, and DELETE statements.

   • Understand Data Definition Language (DDL) for creating and modifying database structures.

   • Work with constraints (PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL) to ensure data integrity.

3. Data Analysis and Aggregation:

   • Explore the power of SQL aggregations with SUM, COUNT, AVG, MAX, MIN, and other functions.

   • Utilize GROUP BY and HAVING clauses to perform complex data analysis.

   • Gain proficiency in window functions for advanced analytical queries.

4. Advanced SQL Techniques:

   • Master the art of writing complex queries with Common Table Expressions (CTEs).

   • Dive into recursive CTEs for hierarchical data processing.

   • Learn how to pivot and unpivot data for reporting and analysis.

5. Database Design and Normalization:

   • Grasp the principles of database design and normalization.

   • Identify and apply normalization techniques to improve database efficiency.

   • Handle denormalized data and understand trade-offs.

6. Performance Optimization and Query Tuning:

   • Optimize SQL queries for performance.

   • Learn indexing strategies to speed up data retrieval.

   • Interpret query execution plans for query optimization.

Sample Questions :

1. How do you use Common Table Expressions (CTEs) to simplify complex queries?

2. What are window functions in SQL, and how are they used?

3. Explain the differences between temporary tables, table variables, and CTEs.

4. How do you handle hierarchical data using SQL?

5. What is the difference between UNION and UNION ALL, and when would you use each?

6. Explain the concepts of database transactions and ACID properties.

7. How do you ensure data consistency and integrity in a multi-user database environment?

8. How do you use the MERGE statement for performing insert, update, and delete operations in a single query?

9. Explain the concept of database denormalization and when it might be appropriate to use it.

10. What are triggers in SQL, and how do they work?

11. How do you use window functions to calculate running totals and moving averages?

12. Explain the differences between PRIMARY KEY, UNIQUE, and FOREIGN KEY constraints.

13. What are recursive common table expressions (CTEs), and when would you use them?

14. How do you use the LAG and LEAD functions to access data from previous and subsequent rows?

15. Explain the purpose of the PARTITION BY clause in window functions.  and many more

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Frequently Asked Questions

How long do I have access to the course materials?

You can view and review the lecture materials indefinitely, like an on-demand channel.

Can I take my courses with me wherever I go?

Definitely! If you have an internet connection, courses on Udemy are available on any device at any time. If you don’t have an internet connection, some instructors also let their students download course lectures. That’s up to the instructor though, so make sure you get on their good side!