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200 Tricky and Advanced SQL Interview Questions

Grand Master Uncategorized Comments Off on 200 Tricky and Advanced SQL Interview Questions 174 views

In this blog of advanced SQL Interview Questions asked in FAANG, we will have all types of questions asked by FAANG and other such top-rated product-based companies. These questions will cover a lot of advanced topics, so we request you to go through the basics of SQL before attempting these questions. Please go through all the advanced SQL Interview Questions asked in FAANG

Even if you are unable to answer some or more questions, you should Google and search for these questions. Or you can also buy our Ace the SQL Interview in FAANG e-book for the detailed solutions to all the questions in this blog, Advanced SQL Interview Questions asked in FAANG.

Make Sure to check our e-book with 2200+ Interview Questions to Become a Full Stack Analytics Professional – This e-book covers 23 topics like SQL, Python, Case Study, ML Algorithms, Data Engineering Topics, Big Data Technologies, Hadoop, Power BI, etc.. But the main point is that each topic is split into questions that are actually asked in the Analytics interviews ranging from fresher to 8-10 years of Analytics or non-Analytics experience

Ace The SQL Interview
Ace The SQL Interview

Basic SQL Questions Asked in Analytics Interviews

  1. What is the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN?
  2. What is the difference between HAVING and WHERE?
  3. What is the purpose of the GROUP BY clause?
  4. Explain the difference between COUNT(*) and COUNT(column_name).
  5. What is the difference between CHAR and VARCHAR?
  6. What is the difference between UNION and UNION ALL?
  7. What are ACID properties in databases?
  8. Explain the difference between DELETE, TRUNCATE, and DROP.
  9. What is a primary key vs. a unique key?
  10. What is the difference between DISTINCT and GROUP BY?
  11. Can we use an aggregate function without the Group by keyword?

JSON Interview Questions

  1. What is JSON?
  2. How does Presto handle JSON data?
  3. What is the syntax for querying JSON data in Presto?
  4. How does Presto handle nested JSON data?
  5. Can you join JSON data with other tables in Presto?
  6. How does Presto handle JSON arrays?
  7. How can you flatten nested JSON data in Presto?
  8. How can you convert JSON data to a relational format in Presto?
  9. How can you use the json_table() function in Presto?
  10.  How do you store JSON data in SQL?
  11. What SQL function is used to extract values from a JSON column?
  12. How do you filter records based on a JSON field value?
  13. What is JSON_TABLE() in SQL?
  14. How do you update a specific key inside a JSON column?
  15. What is the difference between JSON_QUERY() and JSON_VALUE()?
  16. How do you check if a key exists in a JSON column?
  17. How can you convert a relational table into JSON format?
  18. How do you parse a nested JSON structure in SQL?
  19. How do you aggregate JSON data from multiple rows?

Date and Time Interview Questions in SQL

  1. Find the number of days between two dates.
  2. Get the current date and time in SQL.
  3. Find employees who joined in the last 6 months.
  4. Extract the year, month, and day from a timestamp.
  5. Convert a string into a DATE format in SQL
  6. Find employees who have birthdays this month.
  7. How do you get the last day of the month for a given date?
  8. Write a query to generate all dates between two given dates.
  9. How do you calculate the age of a person from a birth date?
  10. Find the week number for a given date.

Most Asked SQL Interview Questions

  1. Find the nth highest salary from an employee table.
  2. Retrieve duplicate records from a table.
  3. Delete duplicate rows while keeping only one copy.
  4. Find employees with the highest salary in each department.
  5. How do you generate a running total in SQL?
  6. How do you find the second maximum value without using LIMIT or TOP?
  7. How do you swap values of two columns in a table?
  8. Write a SQL query to transpose rows into columns.
  9. Write a SQL query to get the cumulative sum of a column.
  10. How do you generate random rows from a table?

SQL Query Optimization Interview Questions

  1. What is an index? How does it help?
  2. What are the different types of indexes?
  3. What is the difference between clustered and non-clustered indexes?
  4. How does indexing impact INSERT and DELETE operations?
  5. Explain partitioning in databases.
  6. What is the difference between sharding and partitioning?
  7. Why should you avoid using SELECT * in queries?
  8. How do you optimize a query that runs slow?
  9. What is a query execution plan, and how do you analyze it?
  10. How do you find unused indexes in a database?

SQL System Design Interview Questions

You can expect these types of questions in the Advanced SQL Interview Questions asked in FAANG

  1. How would you design a database for an e-commerce system?
  2. How do you efficiently store and query time-series data?
  3. What are the best practices for handling large datasets in SQL?
  4. How do you ensure data consistency across multiple database nodes?
  5. What is database sharding, and how does it work?
  6. How do you handle schema changes in a production database?
  7. How would you design a real-time analytics system in SQL?
  8. What are database migrations, and how do you manage them?
  9. What is the best way to store and retrieve hierarchical data in SQL?
  10. How do you monitor and improve SQL database performance over time?
  11. What is the ACID property in a database?

Transactions and Concurrency Interview Questions

  1. What are the different types of database locks?
  2. Explain the concept of deadlocks in SQL.
  3. What is the difference between pessimistic and optimistic locking?
  4. How do you prevent deadlocks in SQL?
  5. Explain the SERIALIZABLE and READ COMMITTED isolation levels.
  6. What is the purpose of the SAVEPOINT command?
  7. How do you roll back a transaction in SQL?
  8. Explain dirty reads, phantom reads, and non-repeatable reads.
  9. What is MVCC (Multi-Version Concurrency Control)?
  10. How do you handle long-running transactions efficiently?

SQL Theory Interview Questions

  1. What is the difference between a heap table and an indexed table?
  2. Explain normalization and its different forms.
  3. What is denormalization, and when should you use it?
  4.  What is a cross join, and when should it be used?
  5. Explain star schema vs. snowflake schema.
  6. What is OLAP vs. OLTP?
  7. How do you design a high-availability database system?
  8. What is the CAP theorem in distributed databases?
  9.  Explain the concept of eventual consistency in NoSQL databases.
  10.  What are the advantages of using NoSQL over SQL?

SQL Hard Interview Questions

You can expect these types of questions in the Advanced SQL Interview Questions asked in FAANG

  1. Write a query to find missing numbers in a sequence.
  2. Given a table with start and end times, find the total overlapping time.
  3. Reverse the order of words in a given column.
  4. Write a query to remove HTML tags from a text column.
  5. Find the longest consecutive sequence of numbers in a column.
  6. Write a query to find the top 3 most common values in a column.
  7. How do you perform fuzzy matching in SQL?
  8. Generate a random password using SQL functions.
  9. JOIN vs. EXISTS vs. IN
  10. Write a query to find all employees reporting to a given manager.
  11. Given a table of room bookings, find overlapping reservations.
  12. Find cases where sales in one month dropped more than 50% compared to the previous month.

Advanced SQL Aggregation Interview Questions

  1. Find Top 3 Sales per Region Using NTILE()
  2. Find Customers Who Made Purchases in Consecutive Months
  3. How do you find months where revenue dropped by more than 30% compared to the previous month?
  4. How do you ensure missing dates appear in the report with zero sales?
  5. Write a query to compute total sales per region, per product, and overall total in a single query.
  6. How do you calculate the percentage of total sales each region contributes?
  7. How do you find the first and last transaction for each customer?
  8. How do you compute a 3-month moving average of sales for each product?
  9. How do you rank products based on total sales in descending order?
  10. Write a query to calculate the cumulative sum of sales per customer, ordered by transaction date.

Advanced Error Handling & Debugging interview questions

  1. How do you prevent a division by zero error when calculating a ratio in SQL?
  2. How do you debug a stored procedure in SQL Server?
  3. How do you handle deadlocks in SQL Server?
  4. What happens when you aggregate a column that contains NULL values? How do you handle it?
  5. How do you debug PL/SQL stored procedures in Oracle?
  6. How do you handle errors inside a MySQL stored procedure?
  7. How do you log errors in PostgreSQL?
  8. How do you handle errors when converting a string to an integer in SQL Server?
  9. How do you ensure that a transaction is rolled back when an error occurs?
  10. How do you capture query execution errors in Oracle?

Stored Procedure and CTE Interview Questions

  1. What is a Stored Procedure, and why use it?
  2. How do you create and execute a Stored Procedure in SQL Server?
  3. How do you handle errors inside a Stored Procedure?
  4. How do you implement a Stored Procedure with an output parameter?
  5. How do you call a Stored Procedure inside another Stored Procedure?
  6. What is the difference between Stored Procedures and Functions?
  7. How do you optimize a Stored Procedure for performance?
  8. What is a Common Table Expression (CTE), and why use it?
  9. What is the difference between a CTE and a Temporary Table?
  10. How do you write a Recursive CTE?
  11. How do you use CTE for pagination?
  12. Can a CTE be used inside a Stored Procedure?

Advanced Joins in SQL Interview Questions

  1. What is a CROSS JOIN, and when do you use it?
  2. How does a SELF JOIN work?
  3. What is an ANTI JOIN, and how do you implement it?
  4. What is a SEMI JOIN? How is it different from INNER JOIN?
  5. How do you use a LATERAL JOIN?
  6. How does INTERSECT work?
  7. What is EXCEPT in SQL?
  8. How do you find duplicate records using set operations?
  9. What are the performance considerations for set operations?
  10. How do you handle NULL values in set operations?

Complex Data Handling Interview Questions

  1. How do you store and retrieve hierarchical data in SQL?
  2. How do you handle multi-valued attributes in SQL?
  3. How do you efficiently update large datasets?
  4. What are the pros and cons of storing BLOBs in a database?
  5. How do you store time-series data efficiently?
  6. How do you store and retrieve encrypted data in SQL?
  7. How do you efficiently delete old records from a large table?
  8. How do you optimize storage for high-volume insertions?
  9. How do you improve read performance for analytical queries?
  10. How do you prevent fragmentation in indexes?

Data Modeling Interview Questions

  1. What is data modeling, and why is it important?
  2. What is an entity-relationship (ER) model?
  3. What is cardinality in data modeling?
  4. Can you explain a scenario where denormalization is useful?
  5. What is a surrogate key, and when should you use it?
  6. What are the differences between a fact table and a dimension table?
  7. What is a snowflake schema vs. a star schema?
  8. How would you model data for a NoSQL document database (e.g., MongoDB)?
  9. When would you choose a relational database over NoSQL?
  10. How do you handle slowly changing dimensions (SCD)?
  11. How do you model real-time streaming data in a database?
  12. How do you design a scalable recommendation system?
  13. How do you handle multi-tenant databases?

SQL Most Asked Query Interview Questions

  1. In an EmployeeDetails table, we have 3 columns:-
    Emp_id, Emp_Name, and Mgr_id

    The Manager id is nothing but the employee id of some employee. Example

    1, A, 2
    2, B, 3
    3, C, 4

    B is the manager of A and C is the manager of B.
  2. Now in the above example, we have used Inner join as a part of the self join, the above will query will work fine for all the employees who have a Manager, but the Managing Director, CEO’s, etc. won’t necessarily have a Manager. What part of the query will you change to make sure all the employees of the company is present in the output.
  3. Execution of SQL Queries in the backend
  4. Write a query to get all the student with name length 10, starting with K and ending with z.
  5. Can you use HAVING command without any aggregate function in SQL?
  6. You have data on people have applied for a lottery ticket. The data consists of their name and ticket number. You have to choose winners by selecting the people present in the alternate rows (the first winner starting from row number 3). Write a query to make things easy to select the winners.
  7. We have the following values
    10000
    10000
    20000
    30000
    30000
    30000
    What would be the result of row number, rank, and dense rank ?
  8. Find all the students who either are male or live in Mumbai ( have Mumbai as a part of their address).
  9. Suppose there are two columns in employee table i.e. emp id and email.Get all the unique domains  like gmail.com, yahoo.com, outlook.com, etc.
  10. Can you join two table without any common column?
  11. Give the output for the following

    SELECT ‘NITIN’+1
    SELECT ‘NITIN’+’1’
    SELECT(SELECT ‘NITIN’)\
    SELECT ‘1’+1
    SELECT 1+’1’
  12. Select case when null=null then ‘Amit’ else ‘Rahul’ end from dual;
    What will be the output of the above query?
  13. Explain character-manipulation functions? Explains its different types in SQL.
    CONCAT
    SUBSTR
    LENGTH
    INSTR
    LPAD
    RPAD
    TRIM
    REPLACE
  14. Get the number of duplicate names and their frequency
    Table – Employee
    Name
    Nitin
    Amit
    Gaurav
    Nitin
    Amit

    Output

    Nitin – 2
    Amit – 2
    Gaurav – 1
  15. You always have a big data i.e. millions of rows in your tables, how would you partition it for optimum performance?
  16. Suppose in class, you have 3n boys and 2n girls with their names tabulated along with their weight and gender. Write a SQL query to separate students alphabetically who are over-weight (55kg for girls, 75kg for boys)
  17. How can you create an empty table from an existing table? Write the steps and explain the working.
  18. What is the use of IFNULL and ISNULL in SQL?
  19. You have got some data in the Table 1 and Table 2
    Write a SQL query to create a Table 3 that contains the following columns- Id, First_Name, Last_Name, Salary
  20. What is CROSS JOIN UNNEST in Presto ?
  21. What is LATERAL VIEW explode in Hive?
  22. Suppose there are two tables, X and Y, X has just one column A and Y has B.

    These are the two tables

    Table X
    Column A
    1
    1
    1

    Table Y
    Column B
    1
    1
    1
    1
    1

    How many rows will be populated if you do
    X left join Y
    X inner join Y
    X cross join Y
    X right join Y
  23. Pivot a table in SQL without using pivot function

    Suppose there are two columns
    Age Name
    25   Nitin
    30   Amit
    27   Rishab
    29   Ankush
    Convert into
    Name   Nitin.  Amit. Rishab. Ankush
    Age.      25.       30.      27.        29
  24. Get all employee detail from EmployeeDetail table whose
    “FirstName” not start with any single character between ‘a-p’
  25. Assume the name of table and columns
    There are two tables with a common column. Which one will take more processing time
    – Outer Join
    – Full Outer Join
    – Cartesian Join
  26. Could you tell output or result of following SQL statements?
    (Hint- In some cases, there may be an error. So, try to locate them and answer accordingly)

    select 5
    select ‘5’
    select count (‘5’)
    select count (5)
    select count (*)
  27. Find the number of people who are from Delhi and have arrived in Patna in the last 7 days
  28. Write a SQL query  to find all the patients who joined in the year 2022.
  29. State the differences between views and tables.
  30. Given a table dbo.users where the column user_id is a unique numeric identifier, how can you efficiently select the first 100 odd user_id values from the table?
  31. What will be the output of the below query, given an Employee table having 10 records?

    BEGIN TRAN
    TRUNCATE TABLE Employees
    ROLLBACK
    SELECT * FROM Employees
  32. There is a table which contains two columns Student and Marks, you need to find all the students, whose marks are greater than average marks i.e. list of above-average students.
  33. How to Show the Max marks and min marks together from student table?
  34. What do we need to check in Database Testing?

SQL Youtube Tutorial

  1. Fetch Duplicate Rows in SQL – https://youtu.be/MGHNrxsHKcg
  2. Like Operator in sql – https://youtu.be/IqMMbH6Jw0w
  3. Substring and Replace in SQL – https://youtu.be/Pzb9tBdXKyc
  4. Aggregate Functions in SQL – https://youtu.be/6H5neKpUz9E
  5. Cumulative Sum in SQL – https://youtu.be/COEEGPXjNbk
  6. Row number() in SQL – https://youtu.be/1actE8UL4yM
  7. Ntile() – https://youtu.be/xbjyXk7oSdY
  8. Rank vs Dense Rank – https://youtu.be/f32Yne_4G00
  9. Where vs Having – https://youtu.be/rtZpbyyQtVk
  10. Lead and Lag – https://youtu.be/U_OQD3XpagQ
  11. Joins – https://youtu.be/_V38OgS1s5M
  12. Keys – https://youtu.be/yPZG6qurO_Q
  13. 1NF and 2NF – https://youtu.be/7CyxIOj9zTs
  14. 3 NF and BCNF – https://youtu.be/VuJ7gnaas5k
  15. Most Asked Interview Questions – https://youtu.be/UGTsPRUIkYg
  16. Odd even rows – https://youtu.be/-tLTAuvHAU0
  17. Delete vs Truncate vs Drop in SQL – https://youtu.be/cSM86aZRhMo
  18. SQL Tricky Analytics Interview Questions – https://youtu.be/MRgZKeYx1NY
  19. Binary Tree in SQL – https://youtu.be/oAD-YUafmB8
  20. Joins Advanced Interview Questions – https://youtu.be/pf_RdiCBQw4
  21. Facebook SQL Interview Questions – https://youtu.be/LDYdcH82IO0
  22. Tricky SQL Interview Questions  Part 2 – https://youtu.be/B8Zy9bcqai0
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About TheDataMonkGrand Master

I am the Co-Founder of The Data Monk. I have a total of 6+ years of analytics experience 3+ years at Mu Sigma 2 years at OYO 1 year and counting at The Data Monk I am an active trader and a logically sarcastic idiot :)

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