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Questions and Answers
What is the primary purpose of a DBMS providing protection or security measures?
What type of database activity involves reading and updating data values?
What is the term for the process of maintaining a database and its associated programs over time?
In a database, what is the primary purpose of a query?
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What are the mini-world entities in the university environment example?
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What is the primary responsibility of applications interacting with a database?
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What is the purpose of 'active' processing in a DBMS?
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What is the term for the process of changing a database to meet new user requirements?
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What is the primary purpose of a conceptual data model in a database?
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What is the term for the activities performed by an application against a database?
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Study Notes
Database Concepts
- A database system has a self-describing nature, with a DBMS catalog storing the description of a particular database (e.g., data structures, types, and constraints) as meta-data.
Characteristics of the Database Approach
- The database approach allows for isolation between programs and data, called program-data independence, which enables changing data structures and storage organization without having to change the DBMS access programs.
Data Abstraction
- A data model is used to hide storage details and present users with a conceptual view of the database.
- Programs refer to the data model constructs rather than data storage details, supporting multiple views of the data.
Sharing of Data and Multi-User Transaction Processing
- The database approach allows for sharing of data among multiple users and multi-user transaction processing, enabling concurrent users to retrieve from and update the database.
Database Users
- System designers and implementors design and implement DBMS packages, interfaces, and test and debug them.
- Tool developers design and implement software systems for modeling and designing databases, performance monitoring, prototyping, test data generation, user interface creation, and simulation.
- Operators and maintenance personnel manage the actual running and maintenance of the database system hardware and software environment.
Advantages of Using the Database Approach
- Controlling redundancy in data storage and development and maintenance efforts.
- Sharing of data among multiple users.
- Restricting unauthorized access to data.
- Providing persistent storage for program objects.
- Providing storage structures (e.g., indexes) for efficient query processing.
- Providing optimization of queries for efficient processing.
- Providing backup and recovery services.
- Providing multiple interfaces to different classes of users.
- Representing complex relationships among data.
- Enforcing integrity constraints on the database.
- Drawing inferences and actions from the stored data using deductive and active rules and triggers.
Additional Implications of Using the Database Approach
- Flexibility to change data structures as new requirements are defined.
- Availability of current information, extremely important for on-line transaction systems.
- DBMS may provide protection or security measures to prevent unauthorized access.
- DBMS may provide "active" processing to take internal actions on data.
- DBMS may provide presentation and visualization of data.
- DBMS may provide maintenance of the database and associated programs over the lifetime of the database application.
Application Activities Against a Database
- Applications interact with a database by generating queries and transactions.
- Applications must not allow unauthorized users to access data.
- Applications must keep up with changing user requirements against the database.
Example of a Database
- Mini-world entities: STUDENTs, COURSEs, SECTIONs (of COURSEs), (academic) DEPARTMENTs, and INSTRUCTORs.
- Relationships between entities:
- SECTIONs are of specific COURSEs.
- STUDENTs take SECTIONs.
- COURSEs have prerequisite COURSEs.
- INSTRUCTORs teach SECTIONs.
- COURSEs are offered by DEPARTMENTs.
- STUDENTs major in DEPARTMENTs.
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Description
Learn about the relationships between entities in a conceptual data model, including sections, courses, students, instructors, and departments. Understand how these entities interact with each other.
