Advanced SQL (DTAN 6120)

Correct Answer B. NoSQL database, because it can efficiently handle unstructured data.

Explanation

NoSQL databases are designed to store, manage, and process large volumes of unstructured or semi-structured data such as JSON, XML, images, and logs. Unlike relational databases, which rely on structured schemas and tables, NoSQL databases offer flexibility, scalability, and high performance for handling dynamic and complex data formats. This makes them well-suited for big data applications, real-time analytics, and content management systems.

Why Other Options Are Wrong

A. Relational database, because it provides strong data integrity.

Relational databases provide strong data integrity but are not optimized for unstructured data. They require fixed schemas, making them inefficient for handling highly variable or document-based data. While relational databases excel in structured data storage, they struggle with scalability and performance in big data environments.

C. They provide a framework for data visualization and reporting.

Cloud databases provide scalability and remote access, but they are not a specific type of database model. A NoSQL database can be deployed in the cloud, but choosing cloud storage does not automatically solve the issue of managing large unstructured datasets.

D.Flat file database, because it is simple to implement.

Flat file databases store data in simple files without relationships, making them inefficient for handling large-scale or unstructured data. They lack query optimization, indexing, and scalability, making them unsuitable for enterprise-level data management.

Correct Answer C. INTEGER

Explanation

The INTEGER (INT) data type is the primary data type used for storing whole numbers in MySQL. It supports both signed and unsigned values, making it suitable for storing IDs, counts, and other numeric values that do not require decimal precision. INTEGER provides efficient storage and indexing, making it ideal for most applications requiring whole numbers.

Why Other Options Are Wrong

A. FLOAT is used to store approximate decimal values and is prone to rounding errors, making it unsuitable for storing precise whole numbers. It is commonly used in scientific and statistical computations rather than for primary key values or count-based data.

B. DOUBLE is another floating-point data type, but it consumes more storage and is typically used for high-precision decimal values, not whole numbers. Unlike INTEGER, DOUBLE supports fractional values, which are not required for storing integer-based data.

D. DECIMAL is specifically designed for fixed-point precision, making it useful for financial and monetary calculations, not whole numbers. While it can store integer values, its extra precision handling makes it unnecessary for non-decimal data storage.

Correct Answer B. Data is the foundation that, when processed, becomes information.

Explanation

Data consists of raw, unprocessed facts, such as numbers, text, or symbols, that lack context or meaning on their own. When data is organized, analyzed, and interpreted, it becomes information that provides meaningful insights for decision-making. For example, a set of test scores (data) can be analyzed to determine class performance trends (information).

Why Other Options Are Wrong

A. Data and information are the same; both refer to processed facts.

Data and information are not the same; data is unprocessed, whereas information is processed and meaningful. Without processing, data remains disorganized and lacks context, making it difficult to derive insights.

C. Information is more important than data in data management.

Information is not necessarily more important than data; rather, both are interdependent. Without reliable data, information would be inaccurate, and without processing, raw data would not be useful for decision-making.

D. Data is irrelevant without the context provided by information

Data is not irrelevant without context, as raw data is still essential for building meaningful information. Proper structuring, analysis, and validation transform data into valuable insights, making data the foundation of information management.

Correct Answer B. Periodic rebuilding, reorganizing, and re-indexing

Explanation

Performance tuning in database administration involves optimizing queries, indexing strategies, and data storage to ensure efficient retrieval and update operations. Rebuilding, reorganizing, and re-indexing help improve query speed by restructuring fragmented indexes, reducing disk I/O, and enhancing data access patterns. These techniques help maintain database efficiency over time.

Why Other Options Are Wrong

A. Data encryption and backup

Data encryption and backup are important for security and disaster recovery but do not directly improve database performance. While encryption can secure sensitive data, it can actually slow down query execution rather than optimize it.

C. Creating new database schemas

Creating new database schemas is a design activity, not a performance tuning measure. Performance tuning focuses on optimizing existing structures, rather than creating new ones from scratch.

D. Implementing user access controls

Implementing user access controls is a security measure, ensuring that only authorized users can perform certain operations. It does not optimize database speed or efficiency but rather protects sensitive data from unauthorized access.

Correct Answer B. REVOKE

Explanation

The REVOKE command is used in SQL to remove previously granted permissions from users, restricting their ability to access, modify, or execute queries on specific database objects. This ensures that unauthorized users cannot read, insert, update, or delete sensitive data. For example, the command:

REVOKE SELECT, INSERT ON Employees FROM user1;

removes the SELECT and INSERT privileges from user1 on the Employees table.

Why Other Options Are Wrong

A.  SELECT

The SELECT command is used to retrieve data from a table but does not manage access permissions. A user must have SELECT privileges granted by an administrator before they can execute this command.

C. GRANT

The GRANT command is used to assign permissions to users, allowing them to access and manipulate data. Since the question asks about restricting access, GRANT would be the opposite of the required action.

D. UPDATE

The UPDATE command is used to modify existing records in a table but does not control user permissions. While restricting UPDATE access may be necessary for security, it must be done using REVOKE, not UPDATE itself.

Correct Answer B. INSERT INTO Employees (name, position) VALUES ('John Doe', 'Developer');

Explanation

The INSERT INTO statement is used to add new records into a table. By specifying the column names and providing corresponding values, the command ensures that the new employee record is successfully inserted into the Employees table. This is a fundamental Data Manipulation Language (DML) operation for adding data to a database.

Why Other Options Are Wrong

A.  UPDATE Employees SET name = 'John Doe', position = 'Developer';

The UPDATE command is used to modify existing records, not to add new ones. Since John Doe is not yet in the table, using UPDATE would result in no changes unless a record with that name already exists. The correct approach for inserting new data is INSERT INTO.

C. SELECT * FROM Employees WHERE name = 'John Doe';

The SELECT command is used to retrieve data, not to insert records into a table. Running SELECT * FROM Employees WHERE name = 'John Doe' will return data if John Doe is already present but will not add a new record.

D. DELETE FROM Employees WHERE name = 'John Doe';

The DELETE command removes existing records from a table. Using DELETE FROM Employees WHERE name = 'John Doe' would remove John Doe's record instead of inserting it. This command is the opposite of what is required to add new data.

Correct Answer B. To ensure the accuracy and consistency of data.

Explanation

Data integrity ensures that data remains accurate, consistent, and reliable throughout its lifecycle in a database. It prevents duplicate, incorrect, or contradictory data through constraints like PRIMARY KEY, FOREIGN KEY, NOT NULL, and UNIQUE. Maintaining data integrity is essential for ensuring correct transactions, accurate reporting, and dependable database operations.

Why Other Options Are Wrong

A. To enhance the speed of data retrieval

Data integrity does not directly enhance retrieval speed; that is achieved through indexing, query optimization, and database tuning. Integrity rules ensure correctness, not necessarily performance.

C. To facilitate user access to the database

Data integrity does not facilitate user access but rather controls how data is stored and maintained. Managing user access is handled by permissions and security policies, not data integrity mechanisms.

D. To reduce the size of the database

Data integrity does not focus on reducing database size; instead, it ensures that stored data is accurate and meaningful. Reducing database size is achieved through normalization, indexing strategies, and archiving unused data, rather than enforcing integrity rules.

Correct Answer B. It is more precise and reliable when dealing with money.

Explanation

The DECIMAL data type is used for financial and monetary calculations because it provides exact precision and prevents rounding errors. Unlike floating-point data types such as FLOAT and DOUBLE, DECIMAL stores numbers with fixed decimal points, ensuring accurate financial computations. This precision is crucial in applications like accounting, invoicing, and tax calculations, where small rounding errors can lead to significant discrepancies.

Why Other Options Are Wrong

A. It allows for faster calculations.

DECIMAL does not allow for faster calculations compared to FLOAT or DOUBLE. Floating-point data types are generally faster because they use approximate representations, but they can introduce rounding errors, which is unacceptable for financial transactions.

C. It requires less storage space than other data types

DECIMAL requires more storage space than FLOAT or DOUBLE because it stores numbers as exact decimal values. While it improves precision, it consumes more memory, making it less efficient for performance-intensive applications.

D. It automatically formats numbers for currency.

DECIMAL does not automatically format numbers for currency. Formatting is handled by application logic or SQL functions like FORMAT(), not by the data type itself. DECIMAL only ensures that numbers are stored accurately.

Correct Answer B. It ensures that all records have a valid entry for that column.

Explanation

The NOT NULL constraint ensures that a column cannot have NULL values, meaning every record must have a valid entry in that field. This is crucial for maintaining data integrity, as certain fields, such as primary keys, email addresses, or order numbers, must always contain valid data. Without NOT NULL, essential fields could be left blank, leading to incomplete or inconsistent records.

Why Other Options Are Wrong

A. It prevents duplicate entries in a column.

The NOT NULL constraint does not prevent duplicate entries; that is the role of the UNIQUE constraint. A column with NOT NULL can still contain duplicate values as long as no NULLs are present. Preventing duplicates requires an additional constraint, such as UNIQUE or PRIMARY KEY.

C. It allows for flexible data entry without restrictions.

The NOT NULL constraint does not allow for flexible data entry, as it forces a value to be provided. While flexibility is important in some cases, NOT NULL ensures that critical fields are always populated, preventing issues caused by missing data.

D. It automatically fills in missing data with default values.

The NOT NULL constraint does not automatically fill in missing data. If a column is NOT NULL and no value is provided, the database will return an error instead of inserting a default value. Default values must be explicitly set using the DEFAULT keyword.