Databases 1.2

Hierarchical Model

tree like structure for storing data

one parent to one or many children

Network Model

graph like structure for storing data

child can have many parents, many-to-many relationships

Common Business Oriented Language

programming language for data processing

uses batch processing instead of real time transactions

COBOL

Object Oriented Programming

method of organizing data that emerged in the 80s

programs are organized around self contained objects

OOP

Object Relational Databases

relational database that is extended to support the storing of objects

allows for custom data types

ORDBMS

Object Oriented Databases

database that stores data as individual objects

XML Hybrid Databases

database type that emerged in the 90s

combines both relational (structured) and non-relational (document) data into one database

Segment

heading within a hierarchical model

can be either parent or a child, contains fields which hold data under that heading

Schema

conceptual organization of an entire database, what is viewed by DBAs

Subschema

portion of database that applications can view and interact with

Data Definition Language (DDL)

commands to create and remove schema components in a database

foundation for modern SQL

Data Manipulation Language (DML)

commands that allow for interaction with a database

Relation

entire table with rows and columns, one row is a single tuple

Tuple

one row within a table that makes up a single record

all data within the row is related to make up a whole piece of information

Attribute

one column within a table, also called fields

same data type is represented by different values within each tuple

RDBMS

management system specifically for relational databases

hides underlying complexities so end user only sees the data stored

End User Interface

whichever interface the user interacts with in order to manipulate data using SQL

program, web interface, command line

SQL Engine

portion of DBMS that runs SQL queries and data requests

not shown to end user, underlying porcesses

Primary Key

column or combination of columns that uniquely identifies a row

cannot contain duplicate values within the same table

Foreign Key

column or combination of columns that refers to a primary key within another table

used to create relations between separate tables

Index

data structure that makes queries more efficient and easy

created for columns that are used often

Constraint

rule that restricts what values can be stored ina particular table or column

Object Oriented Data Model (OODM)

model of storing both the data and it’s relationships within an object instead of fleshed out rows and columns

Object/Relational Models (O/R)

database model that conforms to the relational structure while allowing objects to be contained within columns

Extended Relational Database Model (ERDM)

model of a relational database that supports extended data types without having the object behaviors integrated into the database

JavaScript Object Notation (JSON)

data storage format for both structure and unstructured data, replaced XML in modern databases

Conceptual Data Models

high level representation of a system’s data requirements and structure

created in early stages of database development

Entity Relationship Diagrams (ERD)

visual representation of the structure of a database and the relationships within it

Cardinality

number of instances of one entity that can be associated with one instance of another entity

one to one, one to many

Associative Entities

entities that exist only to associate data in one entity to data in another entity

Logical Model

next step after the conceptual model, closer to the actual database

create standardization and primary and foreign keys

Normalization

applying database design concepts to reduce duplication and enhance query efficiency and integrity

Physical Model

optimizing a logical model for a specific DBMS

defining data types, security, and overall execution