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Associative entity

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An entity type that associates the instance of one or more entity types and contains attributes that are preculiar to the relationship between those entity instances

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Attribute

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"A property or characteristic of an entity or relationship type that is of interest to the organization.

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Attribute

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Required vs Optional

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Attribute

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Simple vs Composite

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Attribute

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Single-valued vs multivalued

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Attribute

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Stored vs derived

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Binary relationship

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A relationship between the instances of two entity types

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Business Rule

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"A statement that defines or constrains some aspect of the business. IT is intended to assert businessstructure or to control or influence the behavior of a business

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A business rules approach is based on the following premises:

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1. They are a core concept in an enterprise because they are an expression of the business policy and guide individual and aggregrate behavior. (Well-structured business rules can be stated in natural language for end users and in a database model for system developers)

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A business rules approach is based on the following premises:

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2.They can be expressed in terms that are familiar to end users. Thus, users can define and then maintain their own rules.

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A business rules approach is based on the following premises:

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3. They are highly maintainable. They are stored in a central repository and each rule is expressed on ly once, then shared throughout the organization. Each rule is discovered and documented only once, to be applied in all systems development projects

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A business rules approach is based on the following premises:

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4. Enforcement of them can be automated through the use of software that can interpret the rules and enforce them using the integrity mechanisms of the dbms"

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Characteristics of a good business rule

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"1. Declarative

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Characteristics of a good business rule

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2.Precise

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Characteristics of a good business rule

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3. Atomic

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Characteristics of a good business rule

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4. Consistent

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Characteristics of a good business rule

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5. Expressible

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Characteristics of a good business rule

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6. Distinct

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Characteristics of a good business rule

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7. Business-Oriented "

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Cardinality constraint

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a rule that specifies the number of instances of one entity that can (or must) be associated with each instance of another entity

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Composite attribute

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An attribute that has meaningful components (attributes)

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Composite identifier

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An identifiers that consists of an composite attribute

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Degree

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The number of entity types that participate in a relationship

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Derived attribute

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An attribute whose values can be calcualted from related attribute values

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entity

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A person, place, object, event, or concept in the user environment about which the orgnaization wishes to maintain data (Such as Customer, Employee, Product, etc...)

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entity instance

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A single occurrence of an entity type

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Entity Relationship Diagram (ERD)

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A graphical representation of an entity-relationship model

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Entity Relationship Model (ER Model)

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A logical representation of the data for an organization or for a buisness area, using entities for categories of data and relationships for associations between entities

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Entity Type

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Collection of entities that share common properties or characterisitics

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Fact

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An association between two or more terms

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Identifier

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An attribute (or combination of attributes) whose value distinguishes instances of an entity type

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Indentifying owner

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The entity type on which the weak entity type depends

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Indetifying relationship

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The relationship between a week entity type and its owner

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Maximum Cardinality

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The maximum number of instances of one entity that may be assoicated with each instance of another entity

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Minimum Cardinality

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The minimum number of instances of one entity that may be associated with each instance of another entity

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Multivalued Attributes

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An attribute that may take on more than one value for a given entity (or relationship) instance

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Optional Attribute

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An attribute that may not have a value for every entity (or relationship) instance with which it is associated

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Relationship Type

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A meaningful association between or among entity types

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Relationship Instance

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An association between or amoung entity instances where each relationship instance associates exactly one entity instance from each particiapting entity type

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Required Attribute

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An attribute that must have a value for every entity (or relationship) instance with which it is associated

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Simple (or atomic) attribute

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An attribute that cannot be broken down into smaller componens that are meaningful to the organization

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Strong Entity Type

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An entity that exists independently of other entity types

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Term

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A word or phrase that has a specific meaning for the business

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Ternary relationship

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A simultaneous relationships among the instances of three entity types

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Time Stamp

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Time value associated with a data value, often indicating when some event occurred that affected the data value

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Unary Relationship

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A relationship between instances of a single entity type

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Weak Entity Type

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An entity whose existence depends on some other entity type

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Data Names should be:

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"1. Relate to Business, not technical

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Data Names should be:

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2. Be meaningful

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Data Names should be:

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3. Be unique

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Data Names should be:

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4. Be readable

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Data Names should be:

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5. Be composed of words taken from an approved list

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Data Names should be:

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6. Be repeatable

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Data Names should be:

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Follow a standard syntax

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Guidelines for Good Data Definitions

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"1. Definitions are gathered from the same sources as all requirements for information systems. Thus the systems and the data analysts should be looking for data objects and their definitions as these sources of information systems requiresments are studied

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Guidelines for Good Data Definitions

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2. Definitions will usually be accompanies by diagrams, such as ERD

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Guidelines for Good Data Definitions

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3. Definitions will be stated in the singular and explain what the data element i, not what it is not. A definiion will use commonly understood terms an abbrevs and stand alon e in its meaning and not embed other definitions within it. It should be consices and concentrate on the essential meaning of hte data, but it may also state such charcters of the data object, such as examples or subtleties"

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Agile Software Development

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An approact to db and software development that emphasizes "Individuals an interactions over processes and tools, working software over comprehensive documentaiton, customer collaboration over contract negotiation, and response to change over following a plan"

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Conceptual Schema

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A detailed technology-independent specification of the overall structure of organizational data

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Constraint

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A rule that cannot be violated by db users

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Data

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Stored representations of objects and events that have meaning and inportance in the user's environment

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Data Independence

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The sparatation of data descriptions from the application programs that use the data

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Data Model

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Graphical Systems used to capture the nature and relationships among data

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Data Modeling and Design Tools

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Software tools that provdie automated support for creating data models

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Data Warehouse

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An integrated decision support database whose content is derived from the various operational databases

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Database

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An organized collection of logically related data

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Database application

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An application program (or set of related programs) that is used to perform a series of database activities (create, read, update, and delete) on behalf of the db users.

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Database Management system (DBMS)

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A software system that is used to create, maintain, and provide controlled access to user database

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Enterprise Data Modeling

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The first step in db development, in which the scope and general contents of organizational dbs are specified

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Enterprise resource planning (ERP)

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A business mgmt system that integrates all functions of the enterprise. ERP systems are software applications that provide the data necessary

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Information

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Data that have been procesed in such a way as to increase the knowledge of the person who uses the data

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Logical Schema

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The representation of a database for a particular data mgmt technology

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Physical Schema

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Specifications for how data from a logical schema are stored in a computer's 2ndary memory by a dbms

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Project

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A planned undertaking of related activities to reach an objective that has a beginning and an end

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Prototyping

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An iterative process of systems development in which requirements are converted to a working system that is continually revised through close work between analysts and users

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Relational Database

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A db that represents data as a colleciton of tables in which all data relationships are represented by common values in related tables

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Repository

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A centralized knowledge base of all data definitions, data relationships, screen and report formats, and other system components

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Systems Development Life Cycle (SDLC)

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The traditional methodology used to develop, maintain, and replace information systems

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User View

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A logical description of some portion of the database that is required by a user to perform some task

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Enterprise Data Modeling

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Done during the Planning Stage of the SDLC

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Enterprise Data Modeling

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Analyze current data processing

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Enterprise Data Modeling

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Analyze the general business functions and their db needs

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Enterprise Data Modeling

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Justify need for new data and dbs in support of business

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Conceptual Data Modelling

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Done during the Planning and Analysis Stage of the SDLC

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Conceptual Data Modelling

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Identify scope of db rqmts for proposed insys

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Conceptual Data Modelling

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Analyze overall data rqmts for business function(s) supported by the db

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Disadvantages of File Processing Systems

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Program-data dependence

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Disadvantages of File Processing Systems

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Duplication of data

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Disadvantages of File Processing Systems

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Limited Data Sharing

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Disadvantages of File Processing Systems

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Lengthy development times

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Disadvantages of File Processing Systems

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Excessive program maintenance

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