Module 1 Flashcards
What is a database?
A collection of data that exists over a long period of time and is structured, persistent, and managed by a DBMS.
What are examples of databases?
A list of friends’ contacts, company employee records, university student records, and library book inventories.
What is a Database Management System (DBMS)?
A complex software system designed to store and manage databases.
What is the difference between a database, database system, and DBMS?
A database is a collection of data, a DBMS manages the database, and a database system is the combination of both.
What are the main advantages of a DBMS?
Minimizes redundancy, improves data integrity, supports concurrent access, enhances security, and ensures reliability.
What are the ACID properties in DBMS transactions?
Atomicity, Consistency, Isolation, Durability.
What is atomicity in database transactions?
A transaction is either fully completed or fully undone—no partial updates.
What is data consistency in DBMS?
Ensures that data follows integrity constraints and remains valid after transactions.
What is isolation in database transactions?
Ensures that concurrent transactions do not interfere with each other.
What is durability in a database?
Once a transaction is committed, its changes persist even after system failures.
What are the disadvantages of file processing systems (FPS) compared to databases?
Data redundancy, storage waste, update anomalies, inconsistency, and lack of centralized control.
What is data redundancy?
The unnecessary duplication of data in multiple locations.
What is data inconsistency?
When different copies of the same data do not match due to redundant storage.
What are the three levels of database abstraction?
Internal (physical), logical (conceptual), and external (user view).
What is a database schema?
The structure that defines how data is organized in a database.
What is a database instance?
The actual stored data in the database at a specific moment in time.
What is logical data independence?
The ability to change the logical schema without modifying application programs.
What is physical data independence?
The ability to change the physical storage structure without affecting the logical schema.
What are the two main types of database languages?
Data Definition Language (DDL) and Data Manipulation Language (DML).
What is DDL (Data Definition Language)?
Defines the database schema, including tables, indexes, and constraints.
What is DML (Data Manipulation Language)?
Allows users to insert, delete, update, and retrieve data from the database.
What are the two main types of database query languages?
SQL (commercial) and Relational Algebra (theoretical).
What is SQL?
A structured query language used to interact with relational databases.
What are the basic components of an SQL query?
SELECT (what to retrieve), FROM (which tables), WHERE (filter conditions).
