DATABASE INFORMATION MODELS Presented By Team Teaching Data

DATABASE & INFORMATION MODELS Presented By Team Teaching

Data vs Information • Data: Collection of letters, numbers or facts • Information: Processed data that provides value

What is Database ? • A database is a repository of data, designed to support efficient data storage, retrieval and maintenance • A database may be specialized to store binary files, documents, images, videos, relational data, multidimensional data, transactional data, analytic data, or geographic data to name a few • Data : stored in various forms, namely tabular, hierarchical and graphical forms

What is a database management system ? • Database Management System (DBMS), • Software system that manages databases • the terms “Database”, “DBMS”, “data server”, “database server” often used interchangeably to refer to a DBMS • Why do we need database software or a DBMS? • • Security Can handle many users with good performance Allows for concurrency while keeping data consistent Protects from disaster

The evolution of database management systems • In the 1960 s, network and hierarchical systems such as CODASYL and IMSTM • A revolutionary paper by E. F. Codd, an IBM San Jose Research Laboratory employee in 1970 The paper titled “A relational model of data for large shared data banks” • The Structured Query Language (SQL) invented by IBM in the early 1970's has been constantly improved through the years • Today many businesses need to exchange information, and the e. Xtensible Markup Language (XML) is the underlying technology that is used for this purpose

The evolution of database management systems , Cont’d…

Introduction to information models and data models • An information model is an abstract, formal representation of entities that includes their properties, relationships and the operations that can be performed on them • Data model : mappings of the Information Model

The difference between information model and data model • The main purpose of an Information Model is to model managed objects at a conceptual level, independent of any specific implementations or protocols used to transport the data • Data Models, on the other hand, are defined at a more concrete level and include many details

Relationship between an Information Model and a Data Model

Types of information models • • • Network (CODASYL): 1970’s Hierarchical (IMS): late 1960’s and 1970’s Relational: 1970’s and early 1980’s Entity-Relationship: 1970’s Extended Relational: 1980’s Semantic: late 1970’s and 1980’s Object-oriented: late 1980’s and early 1990’s Object-relational: late 1980’s and early 1990’s Semi-structured (XML): late 1990’s to the present

Network model • In 1969, CODASYL (Committee on Data Systems Languages) released its first specification about the network data model • This followed in 1971 and 1973 with specifications for a record-at-a-time data manipulation language

Hierarchical model • • • The first hierarchical database management system was IMS (Information Management System) released by IBM in 1968. It was originally built as the database for the Apollo space program to land the first humans on the moon. IMS is a very robust database that is still in use today at many companies worldwide

Relational model • 1970’s and early 1980’s • The relational data model is simple and elegant • It has a solid mathematic foundation based on sets theory and predicate calculus and is the most used data model for databases today

Entity-Relationship model • In the mid 1970’s, Peter Chen proposed the entityrelationship (E-R) data model • He proposed thinking of a database as a collection of instances of entities

Object-relational model • The Object-Relational (OR) model is very similar to the relational model • treats every entity as an object (instance of a class), and a relationship as an inheritance

Other data models • The last decade has seen a substantial amount of work on semi-structured, semantic and object oriented data models • XML is ideal to store semi-structured data • Object oriented data models are popular in universities, but have not been widely accepted in the industry

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