Top-down vs Bottom-up Database Design

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Top-down vs Bottom-up Database Design

Database design can be approached in two primary ways: top-down and bottom-up. Each approach has its own methodology for structuring and organizing data within a database system.

See also: Three-level Data Modeling in Databases

Top-down Approach

  • Starts with a high-level overview of the system and breaks it down into smaller components
  • Conceptual level -> Logical level
  1. Define Entity-Relationship (ER) diagrams to capture business requirements
  2. Convert ER diagrams into relational schemas (tables, columns, keys)
  3. Normalize the database to eliminate redundancy and ensure data integrity

Bottom-up Approach

  • Starts with detailed data requirements and builds up to a complete system
  • Better for existing systems where data is already defined
  • Logical level -> Conceptual level
  1. Define tables based on existing data and application needs
  2. Normalize tables to ensure data integrity
  3. Create ER diagrams to represent the overall database structure