Database Management System Prepared by Dr. Ahmed El-Ragal Reviewed & Presented By Mr. Mahmoud Rafeek Alfarra College Of Science & Technology- Khan younis Information Technology & Computer Science Dep. Part 1 The Database Environment

Definitions Database: organized collection of logically related data. Database: organized collection of logically related data. Data: stored representations of meaningful objects and events Data: stored representations of meaningful objects and events Structured: numbers, text, dates Structured: numbers, text, dates Unstructured: images, video, documents Unstructured: images, video, documents Information: data processed to increase knowledge in the person using the data. Information: data processed to increase knowledge in the person using the data. Metadata (data dictionary, system catalog): data that describes the properties and context of user data. Metadata (data dictionary, system catalog): data that describes the properties and context of user data. Reviewed By Mr. Mahmoud Rafeek Alfarra

Descriptions of the properties or characteristics of the data, including data types, field sizes, allowable values, and data context Reviewed By Mr. Mahmoud Rafeek Alfarra

Database Management System DBMS manages data resources like an operating system manages hardware resources A software system that is used to create, maintain, and provide controlled access to user databases Reviewed By Mr. Mahmoud Rafeek Alfarra

Enterprise Data Model Graphical model showing high-level entities and relationships for the organization Reviewed By Mr. Mahmoud Rafeek Alfarra

One customer may place many orders, but each order is placed by a single customer  One-to-many relationship Reviewed By Mr. Mahmoud Rafeek Alfarra

One order has many order lines; each order line is associated with a single order  One-to-many relationship Reviewed By Mr. Mahmoud Rafeek Alfarra

One product can be in many order lines, each order line refers to a single product  One-to-many relationship Reviewed By Mr. Mahmoud Rafeek Alfarra

Therefore, one order involves many products and one product is involved in many orders  Many-to-many relationship Reviewed By Mr. Mahmoud Rafeek Alfarra

Workgroup database with local area network Reviewed By Mr. Mahmoud Rafeek Alfarra

An enterprise data warehouse Enterprise constraints: additional rules specified by the users or database administrators of a database. Reviewed By Mr. Mahmoud Rafeek Alfarra

Components of the Database Environment CASE Tools – computer-aided software engineering CASE Tools – computer-aided software engineering Repository – centralized storehouse of metadata Repository – centralized storehouse of metadata Database Management System (DBMS) – software for managing the database Database Management System (DBMS) – software for managing the database Database – storehouse of the data Database – storehouse of the data Application Programs – software using the data Application Programs – software using the data User Interface – text and graphical displays to users User Interface – text and graphical displays to users Data Administrators – personnel responsible for maintaining the database Data Administrators – personnel responsible for maintaining the database System Developers – personnel responsible for designing databases and software System Developers – personnel responsible for designing databases and software End Users – people who use the applications and databases End Users – people who use the applications and databases Reviewed By Mr. Mahmoud Rafeek Alfarra

Components of the database environment Reviewed By Mr. Mahmoud Rafeek Alfarra

Evolution of DB Systems Flat files s s Flat files s s Hierarchical – 1970s s Hierarchical – 1970s s Network – 1970s s Network – 1970s s Relational – 1980s - present Relational – 1980s - present Object-oriented – 1990s - present Object-oriented – 1990s - present Object-relational – 1990s - present Object-relational – 1990s - present Data warehousing – 1980s - present Data warehousing – 1980s - present Web-enabled – 1990s - present Web-enabled – 1990s - present Reviewed By Mr. Mahmoud Rafeek Alfarra

Enterprise Data Model First step in database development First step in database development Specifies scope and general content Specifies scope and general content Overall picture of organizational data at high level of abstraction Overall picture of organizational data at high level of abstraction Entity-relationship diagram Entity-relationship diagram Descriptions of entity types Descriptions of entity types Relationships between entities Relationships between entities Business rules Business rules Reviewed By Mr. Mahmoud Rafeek Alfarra

Segment from enterprise data model Enterprise data model describes the high-level entities in an organization and the relationship between these entities Reviewed By Mr. Mahmoud Rafeek Alfarra

Two Approaches to DB and IS Development SDLC SDLC System Development Life Cycle System Development Life Cycle Detailed, well-planned development process Detailed, well-planned development process Time-consuming, but comprehensive Time-consuming, but comprehensive Long development cycle Long development cycle Prototyping Prototyping Rapid application development (RAD) Rapid application development (RAD) Define database during development of initial prototype Define database during development of initial prototype Repeat implementation and maintenance activities with new prototype versions Repeat implementation and maintenance activities with new prototype versions Reviewed By Mr. Mahmoud Rafeek Alfarra

Systems Development Life Cycle Project Identification and Selection Project Initiation and Planning Analysis Physical Design Implementation Maintenance Logical Design enterprise modeling conceptual data modeling logical database design physical database design database implementation database maintenance System Development Life Cycle (SDLC) is the overall process of developing information systems through a multi step process from investigation of initial requirements through analysis, design, implementation and maintenance. There are many different models and methodologies, but each generally consists of a series of defined steps or stages. Reviewed By Mr. Mahmoud Rafeek Alfarra

Packaged Data Models Model components that can be purchased, customized, and assembled into full-scale data models Model components that can be purchased, customized, and assembled into full-scale data models Advantages Advantages Reduced development time Reduced development time Higher model quality and reliability Higher model quality and reliability Two types: Two types: Universal data models Universal data models Industry-specific data models Industry-specific data models Reviewed By Mr. Mahmoud Rafeek Alfarra

Database Schema Physical Schema (Physical structures) Physical Schema (Physical structures) The physical representation of the database on the computer, this level describes how the data is stored in the DB The physical representation of the database on the computer, this level describes how the data is stored in the DB Conceptual Schema (E-R models) Conceptual Schema (E-R models) The community view of the database, this level describes what data is stored in the DB and the relationship among the data. The community view of the database, this level describes what data is stored in the DB and the relationship among the data. External Schema External Schema The users’ view of the DB, this level describes that part of the database that is relevant to each user The users’ view of the DB, this level describes that part of the database that is relevant to each user User Views User Views Subsets of Conceptual Schema Subsets of Conceptual Schema Can be determined from business-function/data entity matrices Can be determined from business-function/data entity matrices DBA determines schema for different user DBA determines schema for different user Reviewed By Mr. Mahmoud Rafeek Alfarra

Different people have different views of the database…these are the external schema The internal schema is the underlying design and implementation Reviewed By Mr. Mahmoud Rafeek Alfarra

Three-tiered client/server database architecture Reviewed By Mr. Mahmoud Rafeek Alfarra