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Questions and Answers
What is the primary purpose of a DBMS providing protection or security measures?
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 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?
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?
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?
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?
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?
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?
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?
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?
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.
