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Questions and Answers
What is a primary advantage of using the database approach in large organizations?
What is a primary advantage of using the database approach in large organizations?
How does the database approach enhance flexibility?
How does the database approach enhance flexibility?
Why is the availability of current information especially important for online transaction systems?
Why is the availability of current information especially important for online transaction systems?
What benefit does economies of scale in database applications provide?
What benefit does economies of scale in database applications provide?
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What feature allows a DBMS to manage different database applications without requiring changes to the access programs?
What feature allows a DBMS to manage different database applications without requiring changes to the access programs?
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Which of the following does NOT relate to the implications of using the database approach?
Which of the following does NOT relate to the implications of using the database approach?
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What does the database approach allow in terms of data item management?
What does the database approach allow in terms of data item management?
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What is metadata in a database system?
What is metadata in a database system?
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What historical development led to the emergence of object-relational DBMSs?
What historical development led to the emergence of object-relational DBMSs?
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Which aspect of a database system helps to prevent unauthorized access?
Which aspect of a database system helps to prevent unauthorized access?
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Which of the following describes a relationship in a typical university database model?
Which of the following describes a relationship in a typical university database model?
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What was one of the earliest types of database models introduced in the 1960s?
What was one of the earliest types of database models introduced in the 1960s?
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Which characteristic of a database systems enhances its flexibility with changing requirements?
Which characteristic of a database systems enhances its flexibility with changing requirements?
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What is an example of active processing in a DBMS?
What is an example of active processing in a DBMS?
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How does a DBMS support maintenance of databases over time?
How does a DBMS support maintenance of databases over time?
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What relationship does a student typically have in a university database?
What relationship does a student typically have in a university database?
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What is one of the main advantages of using a database approach?
What is one of the main advantages of using a database approach?
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Which of the following is NOT an advantage of using the database approach?
Which of the following is NOT an advantage of using the database approach?
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How do databases enforce integrity constraints?
How do databases enforce integrity constraints?
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What role does efficient query processing play in the advantages of using databases?
What role does efficient query processing play in the advantages of using databases?
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Which statement accurately describes persistent storage in database systems?
Which statement accurately describes persistent storage in database systems?
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What is a potential benefit of having multiple interfaces in database systems?
What is a potential benefit of having multiple interfaces in database systems?
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What is one way databases can manage complex relationships among data?
What is one way databases can manage complex relationships among data?
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How does a database provide backup and recovery services?
How does a database provide backup and recovery services?
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Study Notes
Fundamentals of Database Systems
- Book Title: Fundamentals of Database Systems
- Edition: 5th
- Authors: Elmasri / Navathe
Chapter 1: Introduction: Databases and Database Users
-
Outline Topics:
- Types of Databases and Database Applications
- Basic Definitions
- Typical DBMS Functionality
- Example of a Database (UNIVERSITY)
- Main Characteristics of the Database Approach
- Database Users
- Advantages of Using the Database Approach
- When Not to Use Databases
Types of Databases and Database Applications
- Traditional Applications: Numeric and textual databases
- More Recent Applications: Multimedia databases, Geographic Information Systems (GIS), Data Warehouses, Real-time and Active Databases, many more
- Later chapters in book describe more recent database applications
Basic Definitions
- Database: A collection of related data.
- Data: Known facts that can be recorded, with implicit meaning.
- Mini-world: A portion of the real world, for example student grades at a University
- DBMS (Database Management System): Software system for creating, maintaining computerized databases
- Database System: DBMS software, the data itself, and sometimes applications
Simplified Database System Environment (Figure 1.1)
- Diagram shows layers of a simplified database system: Users/Programmers, Application Programs/Queries, DBMS Software, Software to Process Queries/Programs, Software to Access Stored Data, Stored Database Definition (Meta-Data)
Typical DBMS Functionality
- Defining Database Structures
- Constructing and Loading Initial Database Contents
- Manipulating the Database: Retrieval (e.g., querying, reporting), Modification (insertions, deletions, updates), Accessing through Web Applications
- Processing and Sharing: By concurrent users and application programs; maintain data validity and consistency
- Other features: Security Measures (prevent unauthorized access), Active Processing (internal actions on data), Presentation and Visualization, Maintenance (database and associated programs throughout the lifetime)
Example of a Database (UNIVERSITY)
- Mini-world: Part of a university environment
-
Entities:
- STUDENTS
- COURSES
- SECTIONS
- DEPARTMENTS
- INSTRUCTORS
Example of Mini-world Relationships
- SECTIONS are of specific COURSES
- STUDENTS take SECTIONS
- COURSES have prerequisite COURSES
- INSTRUCTORS teach SECTIONS
- COURSES are offered by DEPARTMENTS
- STUDENTS major in DEPARTMENTS
Example of a Simple Database (Figure 1.2)
- Shows sample data for COURSES, SECTIONS, and GRADE REPORT tables
- Includes a PREREQUISITE table
Main Characteristics of the Database Approach
- Self-describing nature: DBMS catalog stores data structure details, types/constraints (meta-data), allowing DBMS to work with different database applications.
- Insulation: Program-Data Independence; allows changing data structures/storage organization without modifying DBMS access programs.
- Example simplified database catalog (Figure 1.3): Shows how relations, columns, associated data types, and relations are defined
Data Abstraction
- Using data models to hide storage details from users, presenting a conceptual view of the database to users
- Programs often refer to data model constructs, not storage details
- Allows multiple views of same database for different users, showing only pertinent information
Sharing of Data and Multi-user Transaction Processing
- Allowing multiple concurrent users to retrieve and update data.
- The DBMS ensures each transaction is processed correctly or aborted
- Recovery subsystem to record changes permanently
- Online Transaction Processing (OLTP) facilitates hundreds of concurrent user transactions per second
Database Users
-
Actors on the Scene: Users who interact with/control database content.
- Those who design, develop, and maintain applications
-
Workers Behind the Scene:
- Database Administrators: Authorize access, coordinate use, and manage resources
- Database Designers: Define content, structure, and constraints; communicate with end-users
Categories of End-Users
- Casual: Access database occasionally
- Naïve/Parametric: Use predefined functions (e.g., bank tellers, reservation clerks)
- Sophisticated: Business analysts, scientists, engineers; use tools that closely interact with database
- Stand-alone: Maintain personal databases using packaged applications (e.g., tax programs, address books)
Advantages of Using the Database Approach
- Controlling data redundancy
- Sharing data among multiple users
- Restricting unauthorized access
- Providing persistent storage for program objects
- Providing structured storage (e.g., indexes) for efficient query processing
- Backup and recovery services
- Providing multiple user interfaces
- Representing complex relationships among data
- Enforcing integrity constraints
- Drawing inferences and taking actions from stored data
Additional Implications of Using the Database Approach
- Enforcing standards (e.g., data item names, display formats)
- Reduced application development time by reducing time added to each new application
- Flexibility to change database structures
- Availability of current information important for online transaction systems (e.g., airline/hotel bookings)
- Economies of scale (avoid wasteful resource duplication)
Historical Development of Database Technology
- Early Database Applications (Hierarchical and Network Models – 1960s-1970s)
- Relational Model (1970s)
- Object-Oriented and Emerging Applications (OODBMSs, ORDBMSs in 1980s-1990s)
Evolution of DB Systems (Figure 1.26)
- Shows progression through different types of databases over time
Example of Network Model Schema (Figure 2.8)
- Illustrates network database model using a diagram
Flat Database Example (Figure 1.28)
- Provides and example of data in a flat database
Network & Hierarchical Database (Figure 1.29)
- Hierarchical Database Structure Diagram
Relational & Object-oriented Database Model (Figure 1.30)
- Database model diagrams for relational and object-oriented models
Extending Database Capabilities
- Additional functionalities being added to DBMSs
- Scientific applications, XML, image/audio/video management, data warehousing/mining, spatial data management, time series management
- Leads to new types of data, complex structures, and indexing schemes
When Not to Use a DBMS
- Main Inhibitors (Costs): Large initial investment in hardware and software; administrative overhead for database functions
- DBMS may be unnecessary: If database/applications are simple, well-defined, and not expected to change; if access by multiple users isn't needed
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