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5 . Database Design

When tasked with building a database system for a small business, the first step is to gather requirements through user interviews and review current activities. Understand the business rules guiding the data. Next, design the database by sketching layouts and documenting the proposed system. Create prototypes for user feedback. Familiarize yourself with data normalization techniques to ensure efficient designs, progressing through First (1NF), Second (2NF), and Third Normal Forms (3NF) to eliminate redundancy and establish proper key relationships. This approach ensures data integrity and system usability.

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5 . Database Design

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  1. CSCI N207 Data Analysis Using Spreadsheets 5. Database Design Lingma Acheson Department of Computer and Information Science IUPUI

  2. What Design is About • You are hired by a small business, and are asked to build a database system. How would you proceed? • There is no data to start with . • Process: • Collect requirements • Interview potential users • Collect sample forms, reports, description of activities • Understand business rules and the nature of data

  3. What Design is About • Design the database • Sketch out the design • Document the design • Envision the future system • Create prototypes (small sample database) • Get feedbacks from the users • Implement the database

  4. Data Normalization • Must know before starting the design! • Different levels of normalization determines how good your table design is. • Relational model revisit:

  5. First Normal Form (1NF) E.g., Create tables to describe the students, advisors and registration information as below:

  6. First Normal Form (1NF) • First Normal Form: No repeating fields Table: REGISTRATION Problem - If we change the room of Jones, we must change it in several places.

  7. Second Normal Form (2NF) • Second Normal Form: Eliminate redundant data Table: REGISTRATION Table: STUDENT_ADVISOR Problem - If we remove one advisor, we will lose a student.

  8. Third Normal Form (3NF) • Third Normal Form: Eliminate data not dependant on key Table: STUDENT Table: REGISTRATION Table: ADVISOR

  9. Third Normal Form (3NF) • Third Normal Form requires creation of primary key and foreign key relationships. • Tables in a certain normalization level must satisfy the requirements of previous levels.

  10. Third Normal Form (3NF) • Fully normalized tables: Table: STUDENT Table: REGISTRATION Table: ADVISOR Table: CLASS

  11. Fourth & Fifth Normal Form • Further normalize the table, not covered in our class.

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