Lesson 2 Flashcards
Data modeling
The process of creating a specific data model for a determined problem domain
Problem domain
A clearly defined area within the real-world environment, with a well-defined scope and boundaries that will be systematically addressed
A 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
Attribute
- A characteristic of an entity or object.
- An attribute has a name and a data type.
One-to-many (1:M or 1…*) relationship
- Associations among two or more entities that are used by data models.
- In a 1:M relationship, one entity instance is associated with many instances of the related entity.
Many-to-many (M:N or …) relationship
Association among two or more entities in which:
- one occurrence of an entity is associated with many occurrences of a related entity &
- one occurrence of the related entity is associated with many occurrences of the first entity.
One-to-one (1:1 or 1…1) relationship
- Associations among two or more entities
- In a 1:1 relationship, one entity instance is associated with only one instance of the related entity.
Constraint
A restriction placed on data, usually expressed in the form of rules
- Each record from first table is associated with many records in second table
- But each record in second table is associated with one record in first table.
What type of relationship is it?
One-to-many (1:M) relationship
Single record in the first table is related to only one record in the second table and vice versa.
What type of relationship is it?
One-to-one (1:1) relationship
Each record from first table is associated with many records in second table and one record in second table is associated with many records in first table
What type of relationship is it?
Many-to-many (M:M) relationship
Business rule
For example, a pilot cannot be on duty for more than 10 hours during a 24-hour period
A description of a policy, procedure, or principle within an organization.
Hierarchical model
An early database model whose basic concepts and characteristics formed the basis for subsequent database development
Segment
In the hierarchical data model, the equivalent of a file system’s record type
Network model
An early data model that represented data as a collection of record types in 1:M relationships.
Schema
A logical grouping of database objects, such as tables, indexes, views, and queries that are related to each other.
Subschema
The portion of the database that interacts with application programs.
Data manipulation language (DML)
The set of commands that allows an end user to manipulate the data in the database, such as SELECT, INSERT, UPDATE, DELETE, COMMIT, and ROLLBACK.
Data definition language (DDL)
The language that allows a database administrator to define the database structure, schema, and subschema
Relational database
a collection of relations that contain the data describing a particular business environment.
Relational model
- Each relation (table) is conceptually represented as a two-dimensional structure of intersecting rows and columns.
- The relations are related to each other through the sharing of common entity characteristics (values in columns).
Relation
A logical construct perceived to be a two-dimensional structure composed of intersecting rows (entities) and columns (attributes) that represents an entity set in the relational model.
Tables are somtimes called ______
Relation
Tuple
In the relational model, a table row.
Relational database management system (RDBMS)
A collection of programs that manages a relational database. The RDBMS software translates a user’s logical requests (queries) into commands that physically locate and retrieve the requested dat
Relational diagram
A graphical representation of a relational database’s entities, the attributes within those entities, and the relationships among the entities.
Entity relationship (ER) Model
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 Peter Chen.
Entity relationship diagram (ERD)
A diagram that depicts an entity relationship model’s entities, attributes, and relations.
Entity instance (entity occurrence)
A row in a relational table
Entity set
A collection of like entities
Connectivity
The type of relationship between entities. Classifications include 1:1, 1:M, and M:N.
What are the 3 types of ER notations?
- Chen notation
- Crow’s foot notation
- class diagram notation
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.
In relational database tables, a _____ describes a row and an ______ describes a column of that table.
Tuple; Attribute
OODM
- Object-oriented data model
- A data model whose basic modeling structure is an object
Object
An abstract representation of a realworld entity that has a unique identity, embedded properties, and the ability to interact with other objects and itself
Object-oriented database management system
- OODBMS
- Data management software used to manage data in an object-oriented database model.
Semantic data model
The first of a series of data models that more closely represented the real world, modeling both data and their relationships in a single structure known as an object.
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.
Method
In the object-oriented data model, a named set of instructions to perform an action. Methods represent real-world actions, and are invoked through messages
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.
Inheritance
In the object-oriented data model, the ability of an object to inherit the data structure and methods of the classes above it in the class hierarchy.
UML
- Unified Model Language
- A language based on object-oriented concepts that provides tools such as diagrams and symbols to graphically model a system.
Class diagram
A diagram used to represent data and their relationships in UML object notation.
_____ is a highly distributed, fault-tolerant file storage system designed to manage large amount of data at high speed.
HDFS (Hadoop Distributed File System)
ERDM
- Extended Relational Data Model
- A model that includes the object-oriented model’s best features in an inherently simpler relational database structural environment.
Object/Relational DBMS (O/R DBMS)
- A DBMS based on the extended relational model (ERDM). The ERDM, championed by many relational database researchers, constitutes the relational model’s response to the OODM.
- This model includes many of the object-oriented model’s best features within an inherently simpler relational database structure.
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.