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11 Cards in this Set

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What are the three other information systems?
4-- Expert systems capture and reproduce the knowledge of an expert problem solver or decision maker and then "stimulate" the thinking of that expert.
5-- Communications and collaboration systems enhance communication and collaboration b/t people, both internal and external to the organization.
6-- office automation systems help employees create and share doucments that support day to day office activites.
What is data modeling?
DM is a technique for organizing and documenting a system's data. (DM is also sometimes called database modeling.)
What is anEntity Relationship Diagram (ERD)?
ERD is a data model utilizing several notations to depict data in terms of the entities and relationships described by that data.
What is an entity?
An entity is a class of persons, places, objects, events, or concepts about which we need to capture (obtain) and store data.
People could be agency, contractor, customers, dept. division.
Places could be sales region, bldg., room, branch office.
Objects -- book, machine, part, product, raw materials, software, license.
Events-- application, award, cancellation, class, flight,invoice, renewal, reservation.

Concepts -- account, block of time, bond, course, fund
What is an instance?
An instance is a single occurrrence of an entity.
What is a data type?
A data type is a property of an atttibute that identifies what type of data can be stored in that attribute
Forexample data types can text only Date, time, or only a number can go in that box.
What is an attribute?
An attribute is a descriptive property or characteristic of an entity. Synonyms for attribute = element, property or field (Field is the one I am used to.)
What is a default value?
A default value is ithe value thatwill be recorded of a value is not specified by a user.
What is a key? -- A key which is a way to identify something under the DM concepts' section of the chapter 8 is described more fully below.
A key is an attribute,or a group of attributes that assumes a unique value for each entity instance. A key is also sometimes called an identifier. While there are four keys the one we need to remember is the primary key. The primary is a candidate key that will most commonly be used to uniquely identify a single entity instance.
What is a relationship?
A relationship a natural business association that exists b/t one or more entities. (The relationship may represent an event that links the entities or merely a logical affinity that exists between entities.)
You can hace a one-to-one relationship, you can have a one ot many relationship, but you can not have a many to many relationship. (Think of not putting in the most specific keywords terms when doing a search and how you get 1 million hits b/c your keywords is a part of many ideas/documents.)
Cardinality is?
Cardinality is the minimum and maximum number of occurrences of one entity that may be related to a single occurrence of the other entity.
(Because all relatiships are bidirectional, cardinality must be defined in both directions for every relationship.)