software-development-lessons

Records and Relationships

This lesson practices domain modeling and when to use a one-to-many or a many-to-many relationship.

Slides

Topics

• domain modeling
• database design

What are the associations?

• Cities and Neighborhoods
• Courses and Students
• Photographers and Photos
• Bands and Venues
• Contractors and Clients
• States and Senators
• Groups and Members

One-to-Many or Many-to-Many?

When you’re deciding, ask yourself:

• Can one x have many y?
• Can one y have many x?

The answer is usually: it depends on what you’re building.

Justify it.

If One-to-Many, which table gets the foreign key column?

If Many-to-Many, what’s a good name for the join table?

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