DBMS practice MCQs covering SQL, normalization, transactions, indexing, and keys for C-CAT exam preparation. Essential revision material for C-CAT aspirants.
Question 1 of 8
Q1
Can a Primary Key column contain a NULL value?
A Primary Key must be unique and non-NULL by definition; it uniquely identifies each row.
Q2
GRANT and REVOKE belong to which SQL command category?
GRANT and REVOKE are DCL (Data Control Language) commands for managing permissions.
Q3
What does 2NF specifically eliminate?
2NF eliminates partial dependencies — non-key attributes must depend on the entire composite key.
Q4
What does 3NF specifically eliminate?
3NF eliminates transitive dependencies — non-key attributes must depend only on the primary key.
Q5
Which join returns all rows from the left table, with NULLs where there's no match in the right?
Correct answer: LEFT JOIN.
Q6
How many clustered indexes can a single table have?
A table can have only one clustered index because it determines the physical storage order of rows.
Q7
In Two-Phase Locking, what happens once a transaction releases its first lock?
In Two-Phase Locking, once a transaction releases its first lock, it enters the shrinking phase and cannot acquire new locks.
Q8
Which ACID property guarantees that committed changes survive a system crash?