Elements of Database System In this Chapter we will Examine • The Relationships among three Elements •People •Software •Technique And how the database approach may be used to develop systems that effectively support organizational needs How to design and structure effective DB System Elements of Database Systems Structure: ◦ Refer to the parts of system and how these part interact ◦ The concern is with blending the five elements into a database system that serve the need of the organization. After this chapter you should understand how hardware, software, people, procedures, and plans can be blended to form an effective database system Elements of Database System How a Database System is like a Campus ◦ When campus or new building is planned ◦ This plan takes into consideration ◦ The special needs ◦ The special characteristics of the site Land is valuable commodity, so it use is carefully planned Data however, may not be recognized as a valuable resource, and often little planning The Need for Planning & Modular Design Database should be compatible with all organizational units. Because this can lead to expensive redundancy and difficult to maintain Think about a building; links between building walls, and whole structure. And they serve the need of the community The Need for Planning & Modular Design A well designed database system consist of ◦ Modules Is used to describe a major element of the overall database system. DBS are loosely coupled and may be built independently, but they should fit into a grander scheme described in DB Master plan. DBSMP lays out the ultimate structure and contents of the database system ◦ Subsystems Of a database system contain data about entities, such as customers and products The need for planning & Modular design Entity: ◦ Is any object, tangible, or intangible, about which the organization wishes to store data. ◦ Entities have attributes such as name, color, price ◦ Entities and attributes must be accessible through some way ◦ The way is called navigation path; ◦ Arrows in database are pointers indicating where the programe should look on the system’s storage device to find record Database system Personal Mgmt module Personal database Marketing module Mkt database The Need for Access, Security, & Adaptability If a building is poorly designed then is that easy to access and so on Someone may be break the building and steal something If it is constructed then it shouldn’t be so expensive to put new things init. So good Database system design is to develop a DBMP DB System Master Plan Suggested outline for DBMP ◦ Organizational environment Goals and objective Organizational structure & function ◦ Elements of the database A major entities and relationship Entity groups Modules User groups Costs and benefits Implementation schedule ◦ Summary DBMS consider Two aspects are important ◦ Organizational goals and objective ◦ The manner in which the enterprise is structured Assist the managers of organizations in measuring the level of goal attainment and in steering the organization towards its goals Entity Charts Purpose of DBMSMP is to guide ◦ Organization to manage its information resources effectively. Information needs at every level of organization ◦ It should identify the major information users and their needs. ◦ It should specify the entities to be contained in DB and relation between them. ◦ Specified entities and relationships can be illustrated in diagram Entity Chart for institute course Instructor Participant Evaluation Prospect Organization Entity chart for institute Entities of interest were ◦ ◦ ◦ ◦ ◦ ◦ Course Instructors Participants Course evaluation Prospects And organization for which prospects work Entity chart Relationship in the diagram are of three types ◦ One-to-one ◦ One-to-many ◦ Many-to-many Details are as….. Entity chart One to one ◦ One instance of an entity of a given type is associated with only one member of another type; such as, a participant in a course fills out one evaluation form for the course. Conversely, a given evaluation form was prepared by one participant Entity chart One to many ◦ One instance of a given type of entity is related to many instance of another type. Such as; one prospects work for one organization, so the line emanating from prospect has a single arrowhead where it terminates with organization. But one organization may have several prospects for a given course. Entity chart Many to many ◦ Relationship is one in which many entities for one type are associated with many instance of another type. Such as, an instructor may teach many different courses, and one course may be taught by many different instructors. Entity Groups Large and complex DBS; can not be designed and build at once. So it should be done piece by piece. The Master plan should describe the major pieces and or modules of the system to be developed How they will work together Structure, relationship and development of it Costs and Benefits Investment they can pay for DBS Cost of development Expensive to develop Could be uncertainty for cost and time Value of the benefits of DBS are more difficult to estimate than cost Thanks very much!! Any Questions????????