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82 Cards in this Set

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  • Back
Data
Data is stored representations of objects and events that have meaning and importance in the user's environment.
Information
Information is data that have been processed in such a way as to increase the knowledge of the person who uses the data.
Metadata
Metadata is data that describe the properties or characteristics of end user dta, and the context of that data.
DBMS
Database Management Systems is a software system that is used to create, maintain, and provide controlled access to user databases.
Disadvantages of File Processing Systems
1) Program-Data Dependence
2) Duplication of Data
3) Limited Data Sharing
4) Lengthy Development Times
5) Excessive Program Maintenance
Enterprise Data Model
A graphical model that shows the high-level entities for the organization and the relationships among those entities.
Database Application
An application program (or set of related prgrams) that is used to perform a series of database activities (create, read, update, and delete) on behalf of database users.
Types of databases
Personal databases, Workgroup databases, Department databases, Enterprise databases
ERP
Enterprise Resource Planning - A business management system that integrates all functions of the enterprise, such as manufacturing, msales, fianance, marketing, inventory, accounting and human resources. ERP systems are software applications that provide the data necessary for the enterprise to examine and manage its activities.
Data Warehouse
An integrated decition support database whose content is derived from the various operational datbases.
Legacy Data
Data contained by a system used prior to the installation of a new system. Legacy data often reside on mainframe systems, which may have been replace by client/server systems or Web-enabled systems.
Extranet
Use of Internet protocols to establish limited access to company data and information by the company's customers and suppliers.
Intranet
Use of Internet protocols to establish access to company data and information that is limited to the organization.
Advantages of the Database Approach
1) Program-Data Independence
2) Minimal Data Redundancy
3) Improved Data Consistency
4) Improved Data Sharing
5) Increased Productivity of Application Development
Data independence
The separation of data descriptions from the application programs that use the data.
User view
A logical description of some portion of the database that is required by a user to perform some task.
Constraint
A rule that cannot be violated by database users
Repository
A centralized knowledge base of all data definitions, data relationships, screen and report formats, and other system components.
Enterprise data modeling
The first step in datbase development, in which the scope and general contents or organizational datbase are specified.
Information systems architecture
A conceptual blueprint or plan that expresses the desired future structure for the information systems in an organization.
Information engineering
A formal, top-down methodology that uses a data orientation to create and maintain information systems.
Top-down planning
A generic iformation systems planning methodology that attempts to gain a broad understanding of the information system needs of the entire organization.
Business function
A related group of business processes that support some aspect of the mission of an enterprise.
Function decomposition
A interative process of breaking down the description of t system into finer and finer detail in which one function is described in greater detail by a set of other, supporting functions.
SDLC
System Development Life Cycle - the traditional methodology used to develop, maintain, and replace information systems.
Steps in SDLC
1) Enterprise modeling
2) Conceptual data modeling
3) Logical database design
4) Physical datbase design and definition
5) Database implementation
6) Datbase maintenance
Prototyping
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.
CASE
Computer-aided software engineering : Software tools that provide automated support for some portion of the systems development process.
Project
A planned undertaking of related activities to reach an objective that has a beginning and an end.
Incremental commitment
A strategy in systems development projects in which the project is reviewed after each phase and continuation of the project is rejustified in each of thse reviews.
Three-Schema Components
1. External schema (mgrs & other emolyees)
2. Conceptual schema (combines all external views into a single view)
3. Internal schema (logical and physical schema)
Conceptual Schema
A detailed, technology-independent specification of the overall structure of organizational data.
Logical Schema
The representation of a database for a particular data managment technology.
Physical Schema
Specifications for how data from a logical schema are stored in a computer's secondary memory by a database management systems
Thre-tiered Database Architecture
1. Cliet tier
2. Application/Web Server tier
3. Enterprise server tier
Client/architecture
A LAN based environment in which database software on a server (called a database server or database engine) performs database commands sent to it from client workstations, and applicatio programs on each client concentrate on user interface functions.
Business rule
A statement that defines or contrains some aspect of the business. It is intended to assert business structure or to control or influence the behavior of the business.
Entity
A prerson, place, obeject, event, or concept in the user environment about which the orgnaization wishes to maintain data.
Entity type
A collection of entities that share common properties or characteristics.
Entity instance
A single occurrence of an entity type
Strong Entity Type
An entity that exists independently of other entity types
Weak entity type
An entity type whose existence depends on some other entity type
Identifying owner
The entity type on which the weak entity type depends
Attribute
A property or characteristic of an entity or relationship type that is interest to the organization.
Required Attribute
An attribute of an entity that must have a value for each entity instance.
Optional attribute
An attribute of an entity that may not have a value for every entity instance.
Composite attribute
An attribute that can be broken down into components parts
Simple (or atomic) attribute
An attribute that cannot be broken down into smaller components.
Multivalued attribute
An attribute that may take on more than one value for a given entity instance.
Identifying relationship
The relationshop between a weak entity type and its owner
Derived attribute
An attribute whse values can be calculated from related attribute values.
Identifier
An attribute (or combination of attributes) that uniquely identifies individual instances of an entity type.
Composite Identifier
An identifier that consists of a composite attribute.
Relationship type
A meaningful association between (or among) entity types.
Relationship instance
An association between (or among) entity instances where each relationshop instance includes exactly one entity from each participating entity type.
Associative entity
An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances.
Degree
THe number of entity types that participate in a relationship.
Unary relationship
A relationship between the instances of a single entity type.
Binary relationship
A relationship between the instances of two entity types.
Ternary relationship
A simultaneous relationship among the instances of three entity types.
Cardinality constraint
Specifies the number of instances of one entity that can (or must) be associated with each intance of another entity.
Mimumum cardinality
The minimum number of instances of one entity that may be associted with each instance of another entity.
Maximum cardinality
The maximum number of instances of one eneity that may be associated with each instance of another entity.
Subtype
A subgrouping of the entities in an tntity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroupings.
Supertype
A generic entity type that has a relationship with one or more subtypes.
Attribute inheritance
A property by which subtype entities inherit values of all attributes of the supertype.
Generalization
The process of defining a more general entity type from a set of more specialized entity types.
Specialization
The process of defining one ore more subtypes of the supertype and ofrming supertupe/subtype relationships.
Completeness constraint
A type of constraint that addresses the question whether an instance of a supertype must also be a member of at least one subtype.
Total specialization rule
Specifies that each entity instance of the supertype must be a member of some subtype in the relationship
Partial specialization rule
Specifies that an entity instance of the supertype is allowed not to belong to any subtype.
Disjointness constraint
A constraint that addresses the question whether an instance of a supertype may simultaneously be a member of two (or more) subtypes.
Disjoint rule
Specifies that if an entity instance (of the supertype) is a member of one subtype, it cannot simultaneously be a memeber of any other subtype.
Overlap rule
Specifies that an entity instance can simultaneously be a member of two (or more) subtypes.
Primary key
An attribute (or combination of attributes) that uniquely identifies each row in a relation.
Composite key
A primary key that consists of more than one attribute
Foreign key
An attribute in a relation of a database that serves as the primary key of another relation in the same database.
Null
A value that may be assigned to an attribute when no other value applies or when the applicable value is unknown.
Entity integrity rule
No primary key attribute (or compoentnt of a primary key attribute) can be null.
Referential integrity constraint
A rule that states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null.
Anomaly
An error or inconsistency that may result when a user attempts to update a table that contains redundant data. The three types of anomalies are insertion, deletion, and modification.
Recursive foreign key
A forign key in a relation that references the primary key values of that same relation.