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Going through SQL advanced interview questions is essential to prepare yourself for those tough interview scenarios. You can do a self-assessment to know if you possess a deep understanding of database management and complex data operations.
Advanced questions help identify individuals who can optimize queries, enhance performance, and solve real-world problems efficiently.
These advanced SQL interview questions cover Indexes, data storage optimization, auto-increment fields, unique identifiers, types of variables, recursive procedures, SQL and NoSQL, Joins, and Keys. Additionally, you will also find questions about Dynamic SQL, Stored Procedures, Collation, and more.
We've compiled this list of advanced SQL interview questions to help you prepare for your upcoming technical interview. Understanding the answers to these questions is essential for acing software engineering and programming interviews.
Popular SQL Advanced Interview Questions with Answers
In this section, we’ll look at some popular SQL advanced interview questions and answers. We’ll also look at some additional practice SQL interview questions to help you prepare for your upcoming technical interview.
Q1. What do you Understand About Indexes in SQL?
Indexes in SQL are used to help retrieve data smoothly and efficiently. There are three main types of indexes in SQL - Unique, Clustered, and Non-Clustered. In SQL, tables can have many non-clustered indexes but only one clustered index.
Q2. What do you do When Data Gets Overloaded in Your Relational Database?
To answer this advanced SQL interview question you can say that if the data is overloaded, you’re ideally required to apply a soft link. A soft link lets you store .idb and .frm files and retrieve them whenever necessary.
Q3. What do you Understand About Auto Increment in SQL?
This is one of the most commonly asked advanced SQL interview questions in technical interviews. Auto Increment is a command through which a unique number is generated immediately when a new record is entered into a table.
Q4. Which Command is Used to Select a Unique Entry or Record in a Table?
To answer this advanced SQL interview question you can say the command used to select a unique entry from the table is - “distinct.” The command used to select a unique entry from the table is - “distinct.”
Q5. What are the Two Types of Variables in SQL?
There are mainly two types of variables in SQL - Local and Global. Local variables are those that exist in a single function. Global variables exist in multiple functions and can be present throughout the program.
Q6. What do you Understand by Recursive Stored Procedure?
The Recursive Stored Procedure is a common procedure through which developers can use the same code snippet multiple times in a program. Through this procedure, code snippets call themselves until a specific boundary condition is reached.
Q7. What is the Main Use of the NVL() Function in SQL?
To answer this advanced SQL interview question you can say that the NVL() function in SQL is essentially used to replace null entries with default values. If the first parameter has a null value, the function returns the next parameter. This is a function that is specific to Oracle databases.
Q8. What is the Unique Constraint in SQL?
To answer this advanced SQL interview question you can say that the Unique Constraint in SQL ensures that every value in a particular record is unique. It prevents identical or similar values in a column from appearing in two different records.
Q9. What are Some Major Differences Between SQL and NoSQL?
This is a common SQL interview question asked in technical interviews.
- SQL is a language used to manage data in relational databases, whereas NoSQL applies to non-relational databases.
- SQL is a language used to store, manage and retrieve structured data, whereas NoSQL is used for unstructured data.
- NoSQL databases scale horizontally while SQL databases scale vertically.
- SQL databases contain data in the form of tables, while NoSQL databases contain data in the form of documents, records, key-values, or graphs.
Q10. What do you Understand About SQL Sandbox?
SQL Sandbox is an environment within the SQL databases where untested programs can be tested and run. There are primarily three types of SQL Sandboxes:
- Sandbox for External Access
- Safe Access Sandbox
- Unsafe Access Sandbox
Additional Advanced SQL Interview Questions for Practice
In this section, we’ll look at some additional Advanced SQL interview questions that often appear in technical interviews.
11. Where is the MyISam table stored in the SQL database?
12. What do you understand about Joins in SQL?
13. What is the fundamental difference between CVarChar2 and Char datatype in SQL?
14. What is the difference between Unique Key and Foreign Key in SQL?
15. What do you understand about Data Integrity, and how do you ensure it in SQL?
16. Explain the differences between the different types of Indexes in SQL
17. Explain the process of Query Optimization in SQL
18. What are the advantages of Normalization in SQL?
19. What is the difference between Truncate and Drop commands in SQL?
20. What do you understand about SQL Injection?
21. What is a Trigger in SQL?
22. Which are the different Operators that are available in SQL?
23. What do you understand about SubQuery in SQL?
24. What are Relationships in SQL? Which are the different types of Relationships in SQL?
25. What do you understand about Clauses in SQL?
26. Which are the ways by which Dynamic SQL can be deployed?
27. Which are the different types of Set Operators available in SQL?
28. What are Scalar and Aggregate functions in SQL?
29. What are the advantages of Stored Procedures in SQL?
30. What do you understand about Collation in SQL?
31. Write a query to find the average order amount for each customer, but also include each order's deviation from this average. Use the Orders table, which includes OrderID, CustomerID, and OrderAmount.
32. Explain what an indexed view is in SQL Server and provide an example of how to create one. Discuss the benefits and potential drawbacks of using indexed views.ludes OrderID, CustomerID, and OrderAmount.
33. Describe the use of Common Table Expressions (CTEs) in SQL Server. Provide an example of a recursive CTE to generate a hierarchy of categories in a product catalog.
34. Explain how Full-Text Search works in SQL Server and provide an example of how to set it up and use it to search for a term within a table of documents.
As a developer, your knowledge of SQL is extensively tested in technical interviews. These 30 advanced SQL interview questions will help you prepare for your upcoming software engineering interview.
Learn to Crack Your Next SQL Interview with IK
Exploring advanced SQL interview questions was just the first step toward Data Engineering interviews. You have to enhance your skills and dive deeper into SQL’s concepts. In addition to just preparing for the interviews, you should also look for programs to gain hands-on experience so that you learn through practicals.
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FAQs: Advanced SQL Interview Questions
1. Is your Knowledge of SQL Tested in Coding and Design Interviews at FAANG+ companies?
Your knowledge of SQL is primarily tested in systems design interviews at FAANG+ companies. Design interviews are a key part of the technical interview process.
2. What do you Understand About SQL Limit?
The SQL Limit is a feature in SQL that limits the number of entries or records returned from a Query. This helps in the consistency and seamless retrieval of information from the database.
3. What are the Different Types of User-Defined Functions in SQL?
There are three main types of user-defined functions in SQL - Inline Table-Valued Functions, Multi-Statement Valued Functions, and Scalar Functions.
4. What are your Main Responsibilities as an SQL Developer?
As an SQL developer, you’re responsible for how data is managed and stored in relational databases. You’ll work closely with database administrators to ensure that the database is secure, responsive, and functions flawlessly.
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