DATABASE PRINCIPLE
A structured collection of related data
designed to manage large bodies of
information
DATABASE
Three Main Purposes of a Database
ORGANIZE, STORE, RETRIEVE
The most important purpose of DATABASE?
RETRIEVE
Method of storing and organizing computer files
FILE BASED SYSTEM
•An abstract model
•Describes how data are represented and
accessed
•Formally define data elements
•Relationships among data elements
What is this?
DATA MODEL
•A map of concepts and their relationship
•Describes the semantic of an organization
•Represent a series of assertions
•Describes the significance to organization;
entity classes, attributes and relationships
CONCEPTUAL DATA MODEL
What are the three elements of hierarchical data model
•Root: highest-level data, data retrieval
•Node: middle-level data, parent and child
•Leaf: terminal data, end node
It Organizes data using two fundamental
constructs:
•Records - Contains fields
•Sets - Define one-to-one relationships between records •One owner, many members
NETWORK DATA MODEL
•First-order predicate logic
•Collections of predicates over a finite
set
•Describing constraints on possible
value, combination of values
WHAT IS THIS?
RELATIONAL DATA MODEL