ch02 Flashcards
(62 cards)
American National Standards Institute (ANSI)
The group that accepted the DBTG recommendations and augmented database standards in 1975 through its SPARC committee.
attribute
A characteristic of an entity or object. An attribute has a name and a data type.
Big Data
A movement to find new and better ways to manage large amounts of Web-generated data and derive business insight from it, while simultaneously providing high performance and scalability at a reasonable cost.
business rule
A description of a policy, procedure, or principle within an organization. For example, a pilot cannot be on duty for more than 10 hours during a 24-hour period, or a professor may teach up to four classes during a semester.
Chen notation
See entity relationship (ER) model.
class
A collection of similar objects with shared structure (attributes) and behavior (methods). A class encapsulates an object’s data representation and a method’s implementation. Classes are organized in a class hierarchy.
class diagram
A diagram used to represent data and their relationships in UML object notation.
class diagram notation
The set of symbols used in the creation of class diagrams.
class hierarchy
The organization of classes in a hierarchical tree in which each parent class is a superclass and each child class is a subclass. See also inheritance.
conceptual model
The output of the conceptual design process. The conceptual model provides a global view of an entire database and describes the main data objects, avoiding details.
conceptual schema
A representation of the conceptual model, usually expressed graphically. See also conceptual model.
connectivity
The classification of the relationship between entities. Classifications include 1:1, 1:M, and M:N.
constraint
A restriction placed on data, usually expressed in the form of rules. For example, “A student’s GPA must be between 0.00 and 4.00.” Constraints are important because they help to ensure data integrity.
Crow’s Foot notation
A representation of the entity relationship diagram that uses a three-pronged symbol to represent the “many” sides of the relationship.
data definition language (DDL)
The language that allows a database administrator to define the database structure, schema, and subschema.
data manipulation language (DML)
The set of commands that allows an end user to manipulate the data in the database. The commands include SELECT, INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK.
data model
A representation, usually graphic, of a complex “real-world” data structure. Data models are used in the database design phase of the Database Life Cycle.
entity
A person, place, thing, concept, or event for which data can be stored. See also attribute.
entity instance
In ER modeling, a specific table row. Also known as an entity occurrence.
entity occurrence
See entity instance.
entity relationship (ER) model (ERM)
A data model that describes relationships (1:1, 1:M, and M:N) among entities at the conceptual level with the help of ER diagrams. The model was developed by P. Chen in 1975.
entity relationship diagram (ERD)
A diagram that depicts an entity relationship model’s entities, attributes, and relations.
entity set
In a relational model, a grouping of related entities.
eventual consistency
A model for database consistency in which updates to the database will propagate through the system so that all data copies will be consistent eventually.
