Database Design Principles

(Essential Principles of Database Design)

Golden Rules of Database Design

• Avoid Duplicate and Redundant Information

  • Increases storage unnecessarily by storing the same data multiple times.
  • Reduces data quality due to potential for inconsistencies if data is modified in one place but not another.
  • Example: Combining customer, order, and product information into a single table leads to duplicate data.
  • Solution: Separate data into distinct tables (e.g., Customers, Orders, Products) to eliminate redundancy.

• Ensure Data Quality

  • Use constraints to maintain data accuracy and completeness.
  • Default Constraints: Automatically apply a default value if none is provided.
  • Check Constraints: Enforce valid range of values within a column.
  • Foreign Key Constraints: Maintain relationships between tables, ensuring referential integrity.

Database Design Process

Step 1: Identify the Purpose of Your Database

• Determine what information you need to track and why.
• Example: A personal music database to track artists, albums, and tracks.

Step 2: Discover and Collect Information

• Gather data points and organize them by entity into tables.
• Engage in exercises of identifying data points for real-world objects (e.g., doctor's office pictures).

Step 3: Transform Information into Database Structure

• Convert gathered information into tables and columns.
• Identify primary keys to enforce uniqueness within tables.
• Designate foreign keys to establish relationships between tables.

Step 4: Normalize and Refine Database Design

• Normalization: Apply a series of rules to eliminate redundancies and enhance data quality.
• Five normal forms exist, but achieving the third normal form is generally sufficient.

Key Components in Database Design

Table Design

• Primary Keys:

  • Unique identifier for each table.
  • Customers: Customer ID
  • Products: Product ID
  • Orders: Order ID
  • Order Details: Composite key (Order ID + Product ID)

• Foreign Keys:

  • Ensure valid relationships between tables.
  • Example: Customer ID in Orders references Customer ID in Customers table.
  • Example: Product ID in Order Details references Product ID in Products table.

Conclusion

• Importance of following database design principles to avoid redundancy and ensure data integrity.
• Effective database design requires careful planning and normalization.
• Design databases by identifying and organizing all necessary data points and relationships.

This overview covers the foundational aspects of effective database design and implementation.