INTRODUCTION
SQL Interview Questions interviews can feel intimidating, especially when you don’t know what kind of questions will be asked. I’ve seen many candidates fail not because they didn’t know SQL, but because they didn’t understand how interviewers think.
Interviewers don’t want perfect syntax. They want clarity, logic, and confidence.
That’s why this article exists.
Here, I’ve compiled the top 84 SQL interview questions and answers for 2026, covering beginner, intermediate, and practical concepts. These are the questions that actually appear in interviews, explained in plain English, without unnecessary theory.
If you understand these, you’ll walk into your SQL interview prepared.
BASIC SQL INTERVIEW QUESTIONS (BEGINNER LEVEL)
1. What is SQL?
SQL stands for Structured Query Language. It is used to store, retrieve, update, and delete data from relational databases.
2. What is a database?
A database is an organized collection of data stored electronically so it can be accessed and managed easily.
3. What is DBMS?
DBMS stands for Database Management System. It is software that helps users interact with databases.
4. What is RDBMS?
RDBMS stands for Relational Database Management System. It stores data in tables with rows and columns.
5. Name some popular RDBMS.
MySQL, PostgreSQL, Oracle, SQL Server, MariaDB.
6. What is a table in SQL?
A table stores data in rows and columns.
7. What is a row?
A row represents a single record in a table.
8. What is a column?
A column represents a specific attribute of data.
9. What is a primary key?
A primary key uniquely identifies each row in a table and cannot be NULL.
10. What is a foreign key?
A foreign key connects one table to another using a common column.
11. What is NULL in SQL?
NULL means no value or missing data. It is not zero or empty space.
12. What is an SQL query?
An SQL query is a command used to interact with data in a database.
13. What is the SELECT statement?
SELECT is used to retrieve data from a table.
14. What does WHERE clause do?
WHERE filters records based on a condition.
15. What is DISTINCT?
DISTINCT removes duplicate values from query results.
16. What is ORDER BY?
ORDER BY sorts data in ascending or descending order.
17. What is LIMIT?
LIMIT restricts the number of rows returned.
18. What is COUNT()?
COUNT() returns the number of rows.
19. What is SUM()?
SUM() returns the total of numeric values.
20. What is AVG()?
AVG() returns the average value.
INTERMEDIATE SQL INTERVIEW QUESTIONS
21. What is a JOIN?
JOIN combines rows from two or more tables.
22. Types of JOINs?
INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN.
23. What is INNER JOIN?
Returns matching rows from both tables.
24. What is LEFT JOIN?
Returns all rows from the left table and matching rows from the right table.
25. What is RIGHT JOIN?
Returns all rows from the right table and matching rows from the left table.
26. What is FULL JOIN?
Returns all rows from both tables.
27. What is a subquery?
A query inside another query.
28. What is a nested subquery?
A subquery inside another subquery.
29. What is a correlated subquery?
A subquery that depends on the outer query.
30. What is GROUP BY?
GROUP BY groups rows with the same values.
31. What is HAVING?
HAVING filters grouped data.
32. Difference between WHERE and HAVING?
WHERE filters rows, HAVING filters groups.
33. What is an index?
An index improves query performance by speeding up searches.
34. Types of indexes?
Clustered and Non-clustered.
35. What is a clustered index?
Defines the physical order of data in a table.
36. What is a non-clustered index?
Stores pointers to actual data rows.
37. What is normalization?
Process of reducing data redundancy.
38. What is denormalization?
Adding redundancy to improve performance.
39. What is a view?
A virtual table created using a SELECT query.
40. Can a view store data?
No, it only shows data.
ADVANCED SQL INTERVIEW QUESTIONS
41. What is a stored procedure?
A precompiled set of SQL statements.
42. What is a function?
A function returns a value after performing operations.
43. Difference between procedure and function?
Functions return values; procedures may not.
44. What is a transaction?
A set of SQL operations executed as a single unit.
45. What is COMMIT?
Saves changes permanently.
46. What is ROLLBACK?
Undo changes.
47. What is ACID?
Atomicity, Consistency, Isolation, Durability.
48. What is a SQL Temp Table?
A temporary table used during query execution.
49. Difference between temp table and table variable?
Temp tables handle large data better.
50. What is a trigger?
Automatically executes when an event occurs.
51. What is CASE statement?
Used for conditional logic in SQL.
52. What is UNION?
Combines results of two queries without duplicates.
53. What is UNION ALL?
Combines results including duplicates.
54. What is INTERSECT?
Returns common records.
55. What is EXCEPT?
Returns records from first query not in second.
56. What is DELETE?
Deletes selected rows.
57. What is TRUNCATE?
Deletes all rows quickly.
58. Difference between DELETE and TRUNCATE?
DELETE is reversible; TRUNCATE is not.
59. What is DROP?
Deletes the entire table.
60. What is a composite key?
A primary key made of multiple columns.
PRACTICAL SQL INTERVIEW QUESTIONS
61. How to find duplicate records?
Use GROUP BY with HAVING COUNT > 1.
62. How to remove duplicates?
Use DISTINCT or DELETE with subquery.
63. How to find second highest salary?
Use ORDER BY with LIMIT or subquery.
64. How to find nth highest value?
Use ranking functions.
65. How to fetch last record?
Use ORDER BY DESC with LIMIT 1.
66. How to fetch first record?
Use LIMIT 1.
67. How to get even records?
Use MOD or % operator.
68. How to get odd records?
Use MOD or % operator.
69. How to rename a column?
Use ALTER TABLE.
70. How to add a column?
Use ALTER TABLE ADD.
71. How to delete a column?
Use ALTER TABLE DROP.
72. How to update records?
Use UPDATE statement.
73. How to count total rows?
Use COUNT(*).
74. How to get max value?
Use MAX().
75. How to get min value?
Use MIN().
76. What is LIKE operator?
Used for pattern matching.
77. What are wildcards?
% and _ symbols in LIKE.
78. What is BETWEEN?
Filters values in a range.
79. What is IN operator?
Checks multiple values.
80. What is NOT IN?
Excludes values.
81. What is EXISTS?
Checks if subquery returns rows.
82. What is COALESCE?
Returns first non-null value.
83. What is IFNULL?
Replaces NULL with a value.
84. What is the order of SQL execution?
FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY → LIMIT
CONCLUSION
SQL interviews are not about memorizing syntax. They are about understanding how data works.
If you truly understand these 84 SQL interview questions and answers, you are already ahead of most candidates. Practice writing queries, explain your logic clearly, and stay calm during interviews.
SQL is a skill that grows with experience — and mastering these questions is a strong step toward success in 2026 and beyond.
