OBJECTIVES Why do businesses have trouble finding the information they need in their information systems? How does a DBMS improve the organization of business information? What are the managerial requirements of a data-base environment? What new technologies make databases more accessible and useful?
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENTA computer system organizes data in a hierarchy that starts with bits and progresses to field, records, files, and databasesBit: Smallest unit of data; binary digit (0,1)Byte: Group of bits that represents a single character (letter, a number or symbol)Field: Group of related bytes ( complete word or a complete number like name, age etc.,) - related words or a complete numberRecord: Group of related fields(such as student’s name, course taken,section,grade etc.,)File: Group of records of same type(students records constitute a course file)Database: Group of related files( course file, financial file, personal history file)
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT File Organization Terms and Concepts
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT File Organization Terms and Concepts Entity: Person, place, thing, event about which information is maintained(An order is a typical entity in a sales order file) Attribute: Description of a particular entity (characteristic or quality, order number, order date, amount, item no., and item quantity ) Key Field: Unique identifier field used to retrieve, update, or sort a record
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT Problems with the Traditional File Environment Data redundancy Program-data dependence Lack of flexibility Poor security Lack of data-sharing and availability
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT Problems with the Traditional File Environment
Data Redundancy-It is the presence of duplicate data in multiple data files. Program Data Independence – it is the tight relationship between data stored in files and the specific programs required to update and maintain those files. Lack of Flexibility-A traditional file system can deliver routine scheduled reports after expensive programming efforts, but it cannot deliver ad hoc reports to respond to anticipated information requirements in a timely fashion. Poor security – Because there is little control of management of data, access to and dissemination of information may out of control Lack of data sharing and availability –It is not easy to obtain information because pieces of information in different files and different parts of the organisation cannot be related to one another, it is virtually impossible information to be shared or accessed in a timely manner.
ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT File Organization Terms and Concepts Order number is the key field because each order is assigned a unique identification number
THE DATABASE APPROACH TO DATA MANAGEMENT Database Management System (DBMS)Database• A collection of data organized to service many applications at the same time by storing and managing data so they appear to be at one location• A collection of data organized to service many applications efficiently by centralising the data and minimising redundant data.• A single data base service multiple applications• Ex: Instead of a Corporation storing employee data in separate information systems and separate files for personnel, payroll and benefits , the Corpotation could create a single common human resources database
THE DATABASE APPROACH TO DATA MANAGEMENT A single HRDB serves multiple applications and also allows a corporation to easily draw together all the Information for various applications. The DBMS acts as the interface between the application programs
THE DATABASE APPROACH TO DATA MANAGEMENT Database Management System (DBMS)Database technology can cut through many of the problems a traditional file organization createsDBMS is a special software to create and maintain a database and enable individual business applications to extract the data they need without having to create separate files or data definitions in their computer programs.
THE DATABASE APPROACH TO DATA MANAGEMENT Database Management System (DBMS)Database technology can cut through many of the problems a traditional file organization createsThe Database Management System (DBMS) is simply a software• which creates and maintains databases• that permits an organisation to cdntralise data, manage them efficiently and provide access to the stored data by application programs.• Eliminates most of the data definition statements found in traditional programs• Acts as interface between application programs and physical data files• Separates logical and physical views of data
THE DATABASE APPROACH TO DATA MANAGEMENT Database Management System (DBMS)Database technology can cut through many of the problems a traditional file organization createsThe logical view presents data as they would be percieved by end users or business specialists whereasPhysical view shows how data are actually organised and structured on physical storage mediaThere is only one physical view of the data but different logical views. The DBMS software makes the physical database available for different logical views presented for various application programsAn employee retirement benefits program might use a logical view of the human resources data base that requires only the employees name, address, social security number, pension plan, and retirement benefits data.
7.2 THE DATABASE APPROACH TO DATA MANAGEMENT Database Management System (DBMS)Components of a Database• Data Definition Language: – Specifies content and structure of database and defines each data element• Data Manipulation Language: – Manipulates data in a database• Data Dictionary: – Stores definitions of data elements, and data characteristics
THE DATABASE APPROACH TO DATA MANAGEMENT Types of Databases• Hierarchical DBMS • Organizes data in a tree-like structure • Prevalent in large legacy systems • Less flexible than RDBMS • Lacks support for English language-like queries• Relational DBMS (RDBMS) • Represents data as 2D tables called ‘relations’ • Relates data across tables based on ‘key’ • Egs: DB2, Oracle, MS SQL Server, MS Access
THE DATABASE APPROACH TO DATAMANAGEMENT Types of Databases
THE DATABASE APPROACH TO DATAMANAGEMENT Types of Databases
THE DATABASE APPROACH TO DATA MANAGEMENT Types of DatabasesThree Basic Operations in a Relational DBMS• Select: Creates subset of rows that meet specific criteria• Join: Combines relational tables to provide users with information• Project: Enables users to create new tables containing only relevant information
THE DATABASE APPROACH TO DATA MANAGEMENT Types of Databases
CREATING A DATABASE ENVIRONMENT Designing Databases Entity-Relationship (ER) Diagram ◦ Methodology for documenting databases illustrating relationships between database entities Normalization ◦ Process of creating small stable data structures from complex groups of data
CREATING A DATABASE ENVIRONMENT Designing Databases
CREATING A DATABASE ENVIRONMENT Designing Databases
7.3 CREATING A DATABASE ENVIRONMENT Designing Databases
7.4 DATABASE TRENDS Multidimensional Data AnalysisOn-line Analytical Processing (OLAP) Multidimensional data analysis Supports manipulation and analysis of large volumes of data from multiple dimensions/perspectives
7.4 DATABASE TRENDSMultidimensional Data Analysis
7.4 DATABASE TRENDS Data Warehouses and DataminingData Warehouse Consolidates current and historical data Supports query tools for management decision makingDatamining Tools for finding hidden patterns and relationships in large pools of data
7.4 DATABASE TRENDSData Warehouses and Datamining
7.4 DATABASE TRENDSData Warehousing and Datamining
7.4 DATABASE TRENDS Databases and the WebThe Web and Hypermedia Databases• Organizes data as network of hyperlinks• Database Server runs a DBMS to provide data• Supports text, graphics, sound, video and executable programs
A database administrator (short form DBA) is a person responsible for the design, implementation, maintenance and repair of an organizations database. They are also known by the titles Database Coordinator or Database Programmer, and is closely related to the Database Analyst, Database Modeller, Programmer Analyst, and Systems Manager. The role includes the development and design of database strategies, monitoring and improving database performance and capacity, and planning for future expansion requirements. They may also plan, co- ordinate and implement security measures to safeguard the database. Employing organizations may require that a database administrator have a certification or degree for database systems (for example, the Microsoft Certified Database Administrator. Some organizations have a hierarchical level of database administrators, generally: Data Analysts/Query designers Junior DBAs Midlevel DBAs Senior DBAs DBA consultants Manager/Director of Database Administration/Information Technology
SKILLS: Strong organizational skills Strong logical and analytical thinker Ability to concentrate and pay close attention to detail Ability to think broadly and consider impacts across systems and within the organizationDUTIES: Transferring Data Replicating Data Maintaining database and ensuring its availability to users Maintaining the data dictionary Controlling privileges and permissions to database users Monitoring database performance Database backup and recovery Database security Stop
The Database Analysts role is to direct, evaluate, review, and manage database resources and services across the organization while ensuring high levels of data quality. This individual is also responsible for developing, implementing, and overseeing database policies and procedures to ensure the integrity and availability of databases and their accompanying software. Where required, the Database Analyst will design, install, monitor, maintain, and performance tune production databases.
Database design is the process of producing a detailed data model of a database. This logical data model contains all the needed logical and physical design choices and physical storage parameters needed to generate a design in a Data Definition Language, which can then be used to create a database. A fully attributed data model contains detailed attributes for each entity. The term database design can be used to describe many different parts of the design of an overall database system. Principally, and most correctly, it can be thought of as the logical design of the base data structures used to store the data. In the relational model these are the tables and views. In an object database the entities and relationships map directly to object classes and named relationships. However, the term database design could also be used to apply to the overall process of designing, not just the base data structures, but also the forms and queries used as part of the overall database application within the database management system (DBMS).[ In a majority of cases, a person who is doing the design of a database is a person with expertise in the area of database design, rather than expertise in the domain from which the data to be stored is drawn e.g. financial information, biological information etc. Therefore the data to be stored in the database must be determined in cooperation with a person who does have expertise in that domain, and who is aware of what data must be stored within the system. This process is one which is generally considered part of requirements analysis, and requires skill on the part of the database designer to elicit the needed information from those with the domain knowledge. This is because those with the necessary domain knowledge frequently cannot express clearly what their system requirements for the database are as they are unaccustomed to thinking in terms of the discrete data elements which must be stored. Data to be stored can be determined by Requirement Specification.[