Databases Chapter 1 Quiz

Chapter 1: Databases and Database Users

• Focuses on fundamentals of database systems and users.
• Book's sixth edition.
• Authors are Elmasri and Navathe.
• Introduces various types of databases: traditional, multimedia, and GIS.
• Discusses data warehouses and online analytical processing (OLAP) systems.
• Explores real-time and active database technology.

Overview

• Traditional database applications store textual or numeric information.
• Multimedia databases store images, audio, and video.
• Geographic Information Systems (GIS) manage and analyze map, weather, and satellite data.
• Data warehouses and OLAP systems extract and analyze business information from large databases.
• Real-time and active databases control industrial and manufacturing processes.

Introduction

• A database is a collection of related data.
• Database facts are recorded with an implied meaning.
• A database is a miniworld or universe of discourse (UoD), a specific aspect of the real world.
• It's organized logically, with inherent meaning, and built for a specific purpose.
• Amazon.com is an example of a large commercial database.

Introduction (cont'd)

• Database Management Systems (DBMS): enable users to create and maintain databases.
• A DBMS is software that coordinates database operations.
• A database system includes the DBMS software plus the data itself, sometimes applications too.
• Defining a database involves specifying data types, structures, and constraints.

Introduction (cont'd)

• Metadata is database definition or descriptive information.
• DBMS store it in database catalogs or dictionaries.
• Manipulating a database involves retrieval (querying, generating reports).
• Modification (insertions, deletions, updates), and accessing the database through Web applications.

Introduction (cont'd)

• Sharing a database involves allowing multiple users and programs to access it simultaneously.
• Application programs query DBMS to retrieve data.
• Transactions cause data to be read and written into the database.

Introduction (cont'd)

• Transactions require security and system protection.
• Databases systems must be maintained, allowing them to evolve over time.

An Example

• A UNIVERSITY database stores student, course, and grade information.
• Data records include STUDENT, COURSE, SECTION, GRADE REPORT, and PREREQUISITE.

An Example (cont'd)

• Data structures are defined by specifying data types per element.
• Examples of types are string of alphabetic characters, integer, etc.
• A simplified diagram (Figure 1.1) shows the database system environment.

An Example (cont'd)

• Creating a UNIVERSITY database involves defining and storing data for students, courses, sections, grades, and prerequisites in separate files.
• Relationships exists in the database.
• Database manipulation includes querying and updating existing data.

An Example (cont'd)

• Sample database queries: retrieve transcripts, list students that took a particular section and their grades, list prerequisites for a course.

An Example (cont'd)

• Sample database updates: changing a student's class, adding a new section, entering grades.

An Example (cont'd.)

• Phases of database design:
• Requirements specification and analysis
• Conceptual design
• Logical design
• Physical design

Defining Metadata

• Metadata: describes the database structure, used by DBMS software.
• A Database catalog is used by DBMS software and database users who need information about the database structure.

Insulation Between Programs and Data

• Program-data independence means independent changes of data structures and storage without altering access programs.
• Program operation independence means the interface is independent of the actual implementation procedure.

Data Abstraction

• Data abstraction hides storage details with a view of the database's structure.
• Programmers work with conceptual data constructs instead of data storage details.
• A model represents a conceptual representation of the data without low-level details of storage or operation methods.

Relations (cont'd)

• Figure 1.3 shows a sample database catalog with relation names and columns.

Support for Multiple Views of the Data

• Each database user has a view restricted to data relevant to their role.
• Views are subsets of data derived from database files.
• Database management systems are designed for many users.

Sharing of Data and Multiuser Transaction Processing

• Multiuser transaction processing allows concurrent user access.
• Concurrency control is used to coordinate updates.
• Online transaction processing (OLTP) allows numerous transactions per second.

Sharing of Data and Multiuser Transaction Processing (cont'd)

• Transactions are central to database apps.
• Isolation property: each transaction is isolated from others.
• Atomicity property: all transaction operations are executed or none are.

Database Users

• Database users are divided into:
• Actors on the Scene: those who use and control database content, design, and develop database applications.
• Workers Behind the Scene: those who create and maintain DBMS software and tools, and database system operators.

Actors on the Scene

• Database administrators (DBAs) authorize access, coordinate and monitor database usage, and acquire software/hardware resources.
• Database designers identify data to be stored and choose appropriate structures to represent and store the data.

Categories of End-Users (cont'd)

• Casual End-Users: access databases occasionally.
• Naïve/Parametric End-Users: use well-defined functions (e.g., bank tellers, reservation clerks).
• Sophisticated End-Users: analysts or scientists familiar with database capabilities.
• Stand-alone End-Users: manage personal databases (e.g., internal databases).

Actors on the Scene (cont'd)

• System analysts determine end-user requirements.
• Application programmers implement these specifications as programs.

Workers Behind the Scene

• DBMS system designers/implementers: create DBMS modules and interfaces.
• Tool developers design and implement tools.
• Operators/maintenance personnel operate/maintain hardware/software.

Advantages of Using the DBMS Approach

• Redundancy control (data normalization), restricting unauthorized access (security subsystem), providing backup and recovery.

Advantages of Using the DBMS Approach (cont'd)

• Efficient query processing (indexes, buffering, caching), providing user interfaces (graphical user interfaces, GUIs), enforcing integrity constraints (referential integrity).

Advantages of Using the DBMS Approach (cont'd)

• Enforce standards, reduce app dev time, and change data structures.
• Improved data availability, economies of scale, but may not be suitable for small apps or real-time apps with strict needs.

Additional Implications of Using the Database Approach

• Adapts to changing data requirements
• On-line transaction systems need current information
• Database consolidation reduces wasteful resource overlap

When Not to Use a DBMS

• Simple apps may not require a DBMS.
• Stringent real-time needs may not be efficiently handled by a cumbersome DBMS.
• Embedded systems with limited resources may not be suitable.
• Multiple user access situations may not require a DBMS.

Test your understanding of the fundamentals of database systems and users with this quiz based on Chapter 1 of Elmasri and Navathe's sixth edition. Explore the various types of databases including traditional, multimedia, and GIS, as well as the concepts of data warehouses and OLAP systems.