DBMS Basics — Set 5
Computers · DBMS मूल बातें · Questions 41–50 of 60
Which of the following is a primary characteristic of a DBMS?
Correct Answer: B. High security and integrity
A DBMS provides robust security features to control who can access or modify data. It also uses constraints to maintain data integrity and accuracy. These features make it superior to traditional paper-based or simple file storage.
What is a 'Database Schema'?
Correct Answer: B. The logical structure of the entire database
A database schema is the skeleton structure that represents the logical view of the entire database. It defines how the data is organized and how the relations among them are associated. It is formulated during the initial design phase.
In the relational model, columns are called attributes and rows are called?
Correct Answer: B. Tuples
The correct answer is 'Tuples'. A tuple is the mathematical term for a row in a relation (table). Each tuple represents a single record in the database. This terminology is standard in computer science textbooks.
Which key uniquely identifies each record in a table and cannot be null?
Correct Answer: A. Primary Key
A primary key is a unique identifier for each row in a database table. It must contain unique values and cannot contain NULL values. It ensures that every record in the table can be specifically addressed.
What does the ACID property 'Atomicity' ensure?
Correct Answer: B. A transaction is treated as a single, indivisible unit
Atomicity ensures that all operations within a transaction are completed successfully; otherwise, the transaction is aborted. This 'all or nothing' approach prevents partial updates. It is fundamental to maintaining database reliability.
Which SQL command is used to retrieve data from a database?
Correct Answer: C. SELECT
The SELECT statement is used to fetch data from a database. It allows users to specify which columns and rows they want to see. It is the most commonly used SQL command.
What is the process of reducing data redundancy called?
Correct Answer: B. Normalization
Normalization is the process of organizing data in a database to avoid duplication. It involves dividing large tables into smaller ones and linking them. This improves efficiency and maintains data consistency.
Which of the following is a popular open-source RDBMS?
Correct Answer: B. MySQL
MySQL is a widely-used relational database management system based on SQL. It is open-source, meaning its code is available for free. It is a popular choice for web applications like WordPress.
A foreign key is used to establish a relationship between?
Correct Answer: B. Two tables in a database
A foreign key is a column in one table that points to the primary key of another table. This link connects the data between the two tables. It helps in maintaining referential integrity across the system.
What is 'Metadata' often described as?
Correct Answer: A. Data about data
Metadata provides information about the characteristics of the data stored in the database. For example, it describes the data type, size, and name of a column. It is stored in the data dictionary of the DBMS.