Chapter 9: Database Management Systems Flashcards
Flat-file Model
Environment in which individual data files are not related to other files
Data attribute
Most elemental piece of potentially useful data in the databse
Data redundancy
State of data elements being represented in all user files
Data storage
Efficient information system that captures and stores data only once and makes this single source available to all users who need it
Data updating
Periodic updating of data stored in the files of an organization
Currency of information
Problem associated with the flat-file model because of it’s failure to update all the user files affected by a change in status; may result in decisions based on outdated information
Task-data dependency
User’s inability to obtain additional information as his or her needs change
Database Management System
Software system that controls access to the data resource (program development, backup and recovery, database usage reporting, database access)
Hierarchical Model
Database model that represents data in a hierarchical structure and permits only a single parent record for each child record
Network Model
Variation of the hierarchical model, allowed two parents for single child record
Relational Model
Data model that is more flexible than traditional navigational models, allows users to create new and unique paths through the database to solve a wide range of business problems
Navigational Model
Model that possesses explicit links or paths among data elements
Structured Model
The data elements for predefined structured paths
Users
Individuals who employ systems, receive information, and act on the information received
Data definition language
Programming language used to define the physical database to the database management system
Internal View
Physical arrangement of records in the database
Schema (conceptual view)
Description of entire database represented logically and abstractly
User view (subschema)
Set of data that particular user needs to achieve his or her assigned tasks, defines how particular user sees the portion of the database authorized to see
Access Method
Technique used to locate records and navigate through the database
Data manipulation language
language used to insert special database commands into application programs written in conventional languages, programming language used by particular DBMS to retrieve, process, and store data
Structured Query Language
Data processing tool for end users and professional programmers to access data in the database directly without the need for conventional programs
Database Administrator
Individual responsible for managing database resource (database planning, design, implementation, operation and maintenance, and change and growth)
Data dictionary
Description of every data element in database
Physical Database
Lowest level of the database containing magnetic spots on magnetic disks
