Systems Chapter 2

Known facts that can be recorded and preserved

-Includes text, graphics, images, music, and video

the processed data presented in a form suitable form suitable for human interpretation

-the same data can be processed in a variety of ways to generate different kinds of information

data providing info about one f more other pieces of data

• concept that applies mainly to electronically archived or presented data and is used to describe the:
• -data definition
• -data structure
• -administration of data files with all contents in context to ease the use of the captured and archived data for further use

used to standardize the storage and retrieval of data elements in a data warehouse; defintes elements of the warehouse and how they work

houses standardized, structured, consistent, integrated, correct, clensed and timely data, extracted from various operational systems in an organization

stores, manipulates, retrieves data from large flat files

typically organized sequentially in a fixed format

-requires each application that uses the file to include the info and meaning about the structure of the data in the file

• -inefficient for handling queries
• -duplication of data
• -data dependency; changes in data require re-programming
• -slow development, high maintenance and fixed queries

• piece of software that allows a user to define, create, and manage access to a database
• -decouples application programs from data
• -data duplication limited; all in one location

• combination of:
• -customer requirements
• -application programs addressing the customer requirements
• -a DBMS
• -a database holding the data

Users, database application, DBMS, database

• computer programs that allow users to manipulate the data in a DBMS through user-friendly interface
• -Personal: single user
• -Departmental: hundreds of users over a network
• -Enterprise: extensions of departmental applications
• -Internet: largest form of info sharing

-Data independence: segregates program and data

-Concurrency Control: handle multiple transactions

-Recovery Services: recovers better than flat files

-Utility services: performs initialization and maintenance operations

structure used to organize and represent our perspective or understanding of a system or a behavior

• 1st: Internal Level
• 2nd: Conceptual Level
• 3rd: External Level

collection of concepts for describing data, its relationships, and its constraints

• -clearer more accurate description of data
• -standard platform enables database designers and end-users to communicate

• Three variables:
• -object-based models (conceptual)
• -record-based models (external)
• -physical data models (internal)

use entities, attributes, and relationships to present information

• Examples:
• -entity-relationship
• -functional data
• -object oriented

• a living or non-living object in the real world
• -person, place, event

• property of an entity
• -name, address of a person

association between entities

• describes data in for of E-R diagram
• -entities=rectangles
• -relationships=diamonds
• -attributes=ovals

used records to present data

record: structure that contains a fixed number of fields to hold a piece of information

• Three types:
• -relational data models
• -network data models
• -hierarchical data models