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m Practice Test Questions And Correct
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Answers (Verified Answers) Plus Rationales b b b b
2026|2027 Q&A | Instant Download Pdf
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1. What is the primary purpose of a database index?
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A. To enforce referential integrity
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B. To store metadata
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C. To speed up data retrieval
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D. To normalize data
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Indexes improve the performance of data retrieval operations by allowing faster
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access to rows in a table.
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2. Which SQL command is used to remove a table and all its data?
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A. DELETE
B. DROP
C. ERASE
D. REMOVE
The DROP command deletes the table structure and its data permanently from th
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e database.
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3. What does ACID stand for in database transactions?
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,A. Access, Control, Input, Delete
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B. Asynchronous, Commit, Integrity, Durability b b b
C. Atomicity, Consistency, Isolation, Durability
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D. Algorithm, Consistency, Isolation, Durability
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ACID ensures reliable processing of database transactions.
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4. In normalization, what is the purpose of converting to 3NF (Third Normal
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Form)?
A. To remove composite keys
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B. To eliminate transitive dependencies
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C. To ensure atomic values
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D. To improve encryption
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Third Normal Form removes transitive dependencies to reduce redundancy and i
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mprove integrity.
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5. Which type of JOIN returns all rows from both tables, matching where
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possible?
A. FULL OUTER JOIN
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B. INNER JOIN b
C. LEFT JOINb
D. RIGHT JOIN b
FULL OUTER JOIN returns all records when there is a match in either left or right ta
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ble.
6. What is the default isolation level in most relational databases?
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A. Read Uncommitted
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B. Repeatable Read b
C. Read Committed
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D. Serializable
Read Committed is commonly the default because it balances consistency and per
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formance.
, 7. Which constraint ensures that values in a column are unique?
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A. CHECK
B. UNIQUE
C. NOT NULL
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D. FOREIGN KEY b
The UNIQUE constraint prevents duplicate values in a column.
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8. Which data model uses tables, rows, and columns?
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A. Hierarchical
B. Object-Oriented
C. Relational
D. NoSQL
Relational databases organize data in tables consisting of rows and columns.
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9. What is a foreign key?
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A. A unique identifier for a record
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B. A key used to link two tables
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C. A key that can be null
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D. A key that has duplicate values
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A foreign key establishes a relationship between columns in different tables.
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10. Which command is used to retrieve data from a database?
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A. INSERT
B. SELECT
C. CREATE
D. UPDATE
SELECT is used to retrieve data from one or more tables.
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11. What is the function of a primary key?
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