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Developing Database Specifications

TRACK 3. Developing Database Specifications. 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.

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Developing Database Specifications

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  1. TRACK 3 Developing Database Specifications

  2. 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.

  3. 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.

  4. Reasons... • Lack of a complete requirement specification. • Lack of an appropriate development methodology. • Poor decomposition of design into manageable components.

  5. Database Planning Systems Definition Requirements Collection and analysis Database Design Application Design DBMS Selection 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

  6. Database Planning Systems Definition Requirements Collection and analysis Database Design Application Design DBMS Selection Implementation Data Conversion and loading Testing Evaluation & Maintenance Prototyping DDLC

  7. DB Specs. Components • Requirements Specification • Database Design Specification The WENDY Example - WENT Database Directory

  8. Requirements Specs. • Statement of the Problem Domain • Objectives • Data Requirements • Transaction Requirements

  9. 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

  10. Relational DB Design Phases • Building the logical/conceptual data model • Building the physical database design

  11. Data Modelling • Entity-Relationship Diagram (ERD) - a tool for modelling data. • 3 major concepts to remember • Entity • Attribute • Relation

  12. 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.

  13. 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.

  14. 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.

  15. Other Concepts • Derived Attributes Example: The AGE is a derived attribute of the formula: BIRTHDAY – CURRENT DATE

  16. Integrity Constraints • Required data • Attribute domain constraints • Entity integrity • Referential integrity

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