Dbms Basics

Which SQL clause is used to filter rows AFTER grouping?

A.HAVING

B.WHERE

C.GROUP BY

D.ORDER BY

What does ACID stand for in database transactions?

A.Atomicity, Consistency, Isolation, Durability

B.Atomicity, Concurrency, Integrity, Durability

C.Availability, Consistency, Isolation, Durability

D.Atomicity, Consistency, Integrity, Distribution

Which normal form removes partial dependencies?

A.2NF (Second Normal Form)

B.1NF

C.3NF

D.BCNF

What is a foreign key?

A.A key in one table that references the primary key of another table

B.A key that is never null

C.A combination of two or more columns

D.A key used for indexing

Which SQL command is used to permanently save a transaction?

A.COMMIT

B.ROLLBACK

C.SAVEPOINT

D.BEGIN

What is a deadlock in DBMS?

A.Two transactions waiting indefinitely for each other to release locks

B.A transaction that runs too long

C.A corrupted database state

D.When a query returns no rows

Which JOIN returns all rows from both tables, with NULLs where no match?

A.FULL OUTER JOIN

B.INNER JOIN

C.LEFT JOIN

D.CROSS JOIN

What is the difference between DELETE and TRUNCATE?

A.DELETE removes specific rows (can be rolled back); TRUNCATE removes all rows (cannot be rolled back in most DBs)

B.They are identical

C.TRUNCATE can use WHERE clause; DELETE cannot

D.DELETE is DDL; TRUNCATE is DML

A relation is in BCNF if for every functional dependency X → Y, X is a:

A.Super key

B.Primary key only

C.Foreign key

D.Candidate key only

What does the SQL DISTINCT keyword do?

A.Removes duplicate rows from the result set

B.Sorts the result set

C.Filters NULL values

D.Groups similar rows

Which isolation level prevents dirty reads but allows non-repeatable reads?

A.READ COMMITTED

B.READ UNCOMMITTED

C.REPEATABLE READ

D.SERIALIZABLE

What is an index in a database?

A.A data structure that speeds up query retrieval at the cost of additional storage

B.A constraint that enforces uniqueness

C.A type of join

D.A stored procedure

In a 1:M relationship, where is the foreign key placed?

A.In the 'Many' side table

B.In the 'One' side table

C.In a separate junction table

D.In both tables

What SQL function returns the number of rows in a group?

A.COUNT()

B.SUM()

C.AVG()

D.MAX()

What is a VIEW in SQL?

A.A virtual table based on a stored SQL query

B.A physical copy of a table

C.A type of index

D.A stored procedure

Which property ensures that once a transaction is committed, it survives system failures?

A.Durability

B.Atomicity

C.Isolation

D.Consistency

What is normalization in DBMS?

A.Process of organizing data to reduce redundancy and improve integrity

B.Process of combining tables into one

C.Process of adding more indexes

D.Process of encrypting data

Which of the following is a NoSQL database?

A.MongoDB

B.MySQL

C.PostgreSQL

D.Oracle

What does SQL's GROUP BY clause do?

A.Groups rows with the same values in specified columns for aggregate functions

B.Sorts result set

C.Joins two tables

D.Filters duplicate rows

What is the result of: SELECT * FROM emp WHERE salary BETWEEN 30000 AND 50000?

A.Rows where salary is ≥ 30000 AND ≤ 50000 (inclusive)

B.Rows where salary is > 30000 AND < 50000 (exclusive)

C.Rows outside the range

D.Rows where salary = 30000 OR salary = 50000

DBMS Basics