Complex SQL Interview Questions for Interview Preparation

For an SQL developer hoping to bag their dream job, mastering complex SQL queries is a must for cracking that SQL interview. In this competitive space, the importance of knowing the kind of complex SQL interview questions you can expect can’t be overstated. This article offers sample complex SQL interview questions to help you assess and direct your SQL interview preparation.

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In this article, we’ll learn:

• Complex SQL Interview Questions and Answers for Experienced Developers
• Complex SQL Interview Questions for Practice
• FAQs on Complex SQL Interview Questions

Complex SQL Interview Questions and Answers for Experienced Developers

Here are some sample complex SQL interview questions and answers to help you with your complex SQL preparation:

Q1. Write a query to get the last record from a table?

select * from Student where RowID = select max(RowID) from Student;

Q2. Write a query to get the first record from a table?

The first record can be fetched in two ways, one similar to the last record case, but with min:

select * from Student where RowID = select min(RowID) from Student;

The other method is by printing just one (first) row of the table:

select * from Student where Rownum = 1;

Q3. Write a query to display the first ten records from a table.

select * from Student where Rownum <= 10;

Q4. Create a table with the same structure with data as in the Student table.

Create table Student2 as Select * from Student;

Q5. Show only common records between two tables.

Select * from Student;

Intersect

Select * from StudentA;

Want to know what SQL interview questions are asked at Facebook? Read this article.

Complex SQL Interview Questions for Practice

Now, check out these frequently asked complex SQL interview questions to gauge your interview preparation:

Complex PL SQL Server Interview Questions

These complex PL SQL server questions regularly feature at tech interviews for SQL developers:

1. Define and describe the usage of a linked server.
2. Name and explain the different types of Joins.
3. Explain the different types of authentication modes.
4. Which stored procedure would you run when adding a linked server?
5. Where do you think the user names and passwords will be stored in the SQL server?
6. How would you add email validation using only one query?

Check out this article for more basic and advanced PL SQL interview questions.

Complex SQL Queries Interview Questions

Interview questions related to complex SQL queries are quite common at interviews for developers. These involve questions like “what SQL query would you use to”:

1. Fetch the number of Weekends in the current month
2. Get the last 5 Records from the Student table
3. Get the common records present in two different tables that have no joining conditions.
4. Display records 5 to 9 from the Employee table.
5. Display the last record of a table
6. Display the third-last record of a table
7. Convert seconds into time format
8. Remove duplicate rows from a table
9. Find the number of duplicate rows
10. Find the fourth-highest score in the Students table using self-join
11. Show the max and min salary together from the Employees table
12. Display date in a DD-MM-YYYY table
13. Create Employee_C table, which is the exact replica of the Employee table
14. Drop all user tables from Oracle
15. Calculate the number of rows in a table without using count
16. Find repeated characters from your name
17. Display department and month-wise maximum salary
18. Find the second-highest salary in the Employee table.
19. Select all the records from the Student table, where the names are either Anu or Dan.
20. Select all the records from the Student table where the name is not Anu and Dan.
21. Get Nth Record from the Student table.
22. Get the 3 Highest salaries records from the Student table
23. Show Odd rows in the Student table
24. Show Even rows in the Student table
25. Get the DDL of a table
26. Get all the records from Employees who have joined in the year 2020.
27. Find the maximum salary of each department.
28. Find all Employees with their managers.
29. Display the name of employees who joined in 2020 and have a salary is greater than 50000.
30. Get the first 5 Records from the Student table.
31. Get information of Employees where Employee is not assigned to any department.
32. Show 1 to 100 Numbers 
33. Find duplicate rows in a table
34. Get the previous month’s last day.
35. Display a string vertically.
36. The marks column in the Student table contains comma-separated values. How would you calculate the number of those comma-separated values?
37. Get the 3rd highest salary using Rank Function.
38. Create a table with its structure the same as the structure of the Student table.
39. Display first 25% records from the Student table
40. Display last 25% records from the Student table
41. Create a table with the same structure and data as the Student table
42. Get only the common records between two tables
43. Get unique records from the table without using distinct keywords.
44. Find the admission date of the Student in YYYY-DAY-Date format.
45. Convert the System time into seconds.
46. Display monthly Salary of Employee given annual salary.
47. Get the first record from the Student table
48. Get the last record from the Student table

To practice more SQL interview questions, read this article.

FAQs on Complex SQL Interview Questions 

Q1. What is a complex SQL query?

Complex SQL queries are parameter queries that go beyond the standard SQL usage of SELECT and WHERE and use two or more parameters. They also often heavily use AND and OR clauses. Complex queries are helpful because we can make more precise and accurate database searches with them. 

Q2. How complex is SQL?

SQL is generally an easy language you can learn in a few weeks if you already understand programming. It can take you longer to learn if you’re new to programming. 

Q3. What is advanced SQL?

Advanced SQL involves experience with administrative roles. An SQL programmer should know hardware layout, user management, replication, and backups.

Q4. What is the difference between simple and complex views in SQL?

Simple views in SQL can contain only one base table. On the other hand, complex views in SQL have more than one base table. Complex views can also have a group by clause, join conditions, and order by clause.

Q5. What SQL skills are considered intermediate?

In intermediate SQL skills, you must know and understand: the working and implementation of indexes, how to write a query across multiple tables, create and modify databases, perform recursive joins and pattern-matching, and subqueries table relations.

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