15 to 30 random questions in 15 to 30 minutes, by the level you choose: er, keys, sql, joins, normalization, transactions and indexing. After you submit you get your score, your strong and weak topics, and the right answer with an explanation for every question.
Want to revise first? Read the DBMS interview questions and answers.
The test covers 12 topics across three levels. Each attempt picks 15 to 30 questions at random, by the level you choose, so every attempt is different.
One question from each level, the way they appear in the test. A new set comes on the 1st of every month. Try it, then open the answer.
students:
id name city dept marks
1 Asha Pune CSE 82
2 Rohan Delhi ECE 67
3 Meena Pune CSE 74
4 Kabir Mumbai ME 58
5 Divya Delhi CSE 91
6 Farhan Pune ECE NULL
7 Lakshmi Chennai ME 74
SELECT name
FROM students
WHERE city IN ('Delhi', 'Chennai')
ORDER BY id;Answer: Rohan, Divya, Lakshmi. IN ('Delhi', 'Chennai') is shorthand for city = 'Delhi' OR city = 'Chennai'. Rohan (id 2), Divya (id 5) and Lakshmi (id 7) match, and ORDER BY id lists them in that order, whatever order IN names the cities.
Answer: 3NF. Keys: AB and AC (C -> B lets AC reach B). Every attribute is prime, so 3NF holds. But C -> B has C on the left, and C is not a superkey (C+ = BC), so BCNF fails. This is the classic 3NF-not-BCNF case.
Answer: Its result is infinite, since every tuple not in Student satisfies it. A safe expression only produces values drawn from the database and its constants. Here any tuple of any values that is not in Student qualifies, which is an infinite set. Relational algebra cannot express it, which is why safe TRC equals algebra.
Take the full DBMS mock test: 15 to 30 questions and 15 to 30 minutes, by level.
A question counts as right only when you pick exactly the right option, or all the right options where it says so; a question left blank counts as wrong. Your score is the share of the test's questions you got right (15 to 30, by level). The result also scores every topic, so you know what to revise before the interview.
Yes. The DBMS mock test is free. You need a free CoreHRx Jobs account to start it, so your score and the topics to work on are saved.
It depends on the level: Easy has 15 questions in 15 minutes, Medium has 20 questions in 20 minutes, Hard has 30 questions in 30 minutes. They are multiple-choice questions picked at random from a larger bank of DBMS questions at your level, so every attempt is different.
The questions cover SQL Queries, Normalization, Concurrency Control, Indexing and Hashing, ER Model, Transactions and ACID, Functional Dependencies, Joins, Keys and Relational Model, Relational Algebra, Recovery, Query Processing. Your result shows how you did in each topic.
Easy: Keys, ER basics, normal forms and simple SQL queries. Medium: Joins, normalization, transactions and indexing. Hard: Concurrency control, recovery, query plans and tricky normal-form cases. Start with Easy and move up.
Only your best DBMS score, and only when it is 60% or more. It shows on the job applications you send on CoreHRx. Lower scores stay private.
Yes, up to 10 tests a day. Each attempt picks questions you have not seen recently first.