Database Management Systems

These flashcards cover essential concepts, definitions, and benefits related to databases and database management systems as presented in the lecture notes.

What is a database?

A database is a collection of structured related data where data are facts that have an implicit meaning.

How is a database constructed?

A database is constructed according to a data model which defines how data and interrelationships can be represented.

What are the disadvantages of file-based models?

Disadvantages include data redundancy and inconsistency, difficulty in accessing data, data isolation, integrity problems, atomicity problems, concurrent-access anomalies, and security problems.

What is data redundancy?

Data redundancy is having the same data on different files, which can lead to data inconsistency.

What is atomicity in database terms?

Atomicity ensures that if a failure occurs, the data can be restored to the consistent state that existed prior to the failure.

What is a database management system (DBMS)?

A DBMS is a collection of software programs that provide functionalities for defining, maintaining, and accessing data stored in a database.

What is a benefit of a DBMS regarding data redundancy?

A DBMS ideally minimizes data redundancy by ensuring that each data item is stored in only one place.

What does it mean for a database to have self-describing nature?

A self-describing database system includes both the database itself and metadata that defines and describes the data and relationships.

What is the significance of multiple views in a database system?

Multiple views allow different users to access a subset of data tailored to their needs.

What are integrity constraints in a database?

Integrity constraints are rules that ensure users enter valid information and maintain data integrity.

What is data abstraction?

Data abstraction is the process of hiding complex details and representing data in a simplified manner in a database system.

What are the three levels of data abstraction?

The three levels are physical level, logical level, and view level.

What does the physical level of data abstraction deal with?

The physical level deals with the physical storage details of data, including how data is stored on storage devices.

What is the role of a database designer?

A database designer is responsible for defining the logical structure of the database, including tables and relationships.

What is a view in a database context?

A view is a customized and simplified presentation of a subset of data for specific users.

What is the definition of an instance in a database?

An instance is the collection of data stored in the database at a particular moment.

What is a database schema?

A database schema is the overall design of the database, considered the 'blueprint' that describes how data relates to other tables.

What are physical schemas?

Physical schemas describe the database design at the physical level.

What do logical schemas describe?

Logical schemas describe the database design at the logical level.

What are subschemas?

Subschemas are different views of the database tailored for various users or groups.

What is the conventional structure of a database schema?

A typical schema includes elements such as ID, Name, Level, GPA, and Phone.

What applications utilize database systems?

Applications include sales, banking, online retailers, universities, and telecommunications.

What are advantages of data sharing in a database system?

Data sharing allows integration of all data for an organization, enhancing information generation.

How does a DBMS enforce security?

A DBMS restricts unauthorized access by defining different access privileges for users.

What is concurrency control in a DBMS?

Concurrency control ensures data remains consistent during simultaneous transactions by multiple users.

What are some database management systems?

Examples include Oracle Database, MySQL, and Microsoft SQL Server.

What is the importance of data retrieval systems?

Efficient data retrieval systems are required to ease access to data and meet user needs.

What does data isolation refer to?

Data isolation refers to the issue of having data scattered across various files, often in different formats.

What issues arise from concurrent access in file-based models?

Concurrent-access anomalies may occur when multiple users attempt to update data simultaneously.

What is the significance of transaction processing in a DBMS?

Transaction processing ensures consistent data during updates and incorporates concurrency control mechanisms.

What are the challenges posed by security problems in file models?

Security problems arise when unauthorized users can access or modify sensitive data.

What does the integration of data within a database system enable?

It enables seamless data sharing and enhances the capability to generate valuable insights.

How does meta-data contribute to a database's self-describing nature?

Metadata defines and describes the data, providing context and information about the structure and relationships.

What is the primary goal of a DBMS?

The primary goal of a DBMS is to provide a way to store and retrieve data conveniently and efficiently.

What role do system administrators play regarding physical data storage?

System administrators are responsible for managing the physical level of data abstraction.

How does a DBMS support multiple user access?

A DBMS allows multiple users to access the same database concurrently through features called concurrency control strategies.

What does view level abstraction achieve for users?

View level abstraction provides users with a tailored view of the database that suits their specific needs.

In the context of databases, what are "entities"?

Entities are meaningful objects or things in the data model that data represents.

What is meant by 'data integrity' in a database?

Data integrity refers to the accuracy and consistency of stored data over its lifecycle.