Presentation on theme: "Developing Database Specifications TRACK 3. Learning Objectives At the end of the session, the participants should be able to Identify the information."— Presentation transcript:
Learning Objectives At the end of the session, the participants should be able to Identify the information requirements of the organisation, resource centre/department, end-user. Identify areas wherein database can address the requirements. Write a database requirement specifications. Identify a minimal database design specification.
Why make specifications? Software Crisis 80-90%-do not meet their performance goals 80%-delivered late and over budget 40%-developments fail or are abandoned < 40%-fully address training and skills requirements < 25% -properly integrate business and technology objectives 10-20%-meets all their success criteria.
Reasons... Lack of a complete requirement specification. Lack of an appropriate development methodology. Poor decomposition of design into manageable components.
Database Planning Systems Definition Requirements Collection and analysis Database Design DBMS Selection Application Design Implementation Data Conversion and loading Testing Evaluation & Maintenance Prototyping DDLC STEP 1 - DATABASE PLANNING Feasibility Study - time frame - resource: budget, people Integrate the database with the overall Information Architecture of the organization
Database Planning Systems Definition Requirements Collection and analysis Database Design DBMS Selection Application Design Implementation Data Conversion and loading Testing Evaluation & Maintenance Prototyping DDLC
DB Specs. Components Requirements Specification Database Design Specification The WENDY Example - WENT Database Directory
Requirements Specs. Statement of the Problem Domain Objectives Data Requirements Transaction Requirements
DB Design Objectives represent the data and the relationships between data required from the database application provide a data model that supports any transactions required on the data specify a minimal design that is appropriately structured to achieve the stated performance requirements for the database application
Relational DB Design Phases Building the logical/conceptual data model Building the physical database design
Data Modelling Entity-Relationship Diagram (ERD) - a tool for modelling data. 3 major concepts to remember Entity Attribute Relation
Other Concepts Entity type Example: FULLTIME FACULTY and PARTTIME FACULTY entities both keep the same sets of attributes like name, address, gender, department, position. The two entities can be generalised as FACULTY, which is the entity type.
Other Concepts Attribute Domain Example: The attribute GENDER can contain only any one of the following values: female, male Simple Attribute Example: Firstname is a simple attribute of the entity PERSON.
Other Concepts Composite Attribute Example: Name is a composite attribute that has three parts-- first name, middle name, last name Multi-valued Attribute Example: Area of expertise attribute can hold one or more values for a particular PERSON record.
Other Concepts Derived Attributes Example: The AGE is a derived attribute of the formula: BIRTHDAY – CURRENT DATE