# Database Relationships

Database Relationships: Database Relationships: an overview, One-to-Many, One-to-One, Many-to-Many.

Updated: November 3, 2026

1. [Database Relationships: an overview](https://www.ask-codey.com/lessons/database-relationships-an-overview) (Apprentice): The three kinds of relationship between tables (one-to-many, one-to-one and many-to-many) and how a diagram shows each.
2. [One-to-Many](https://www.ask-codey.com/lessons/database-relationships-one-to-many) (Apprentice): How a one-to-many relationship links many child rows to one parent row through a foreign key, like a customer and their orders.
3. [One-to-One](https://www.ask-codey.com/lessons/database-relationships-one-to-one) (Apprentice): How a one-to-one relationship uses the child table's primary key as its foreign key, and why you would move rarely used data into its own table.
4. [Many-to-Many](https://www.ask-codey.com/lessons/database-relationships-many-to-many) (Journeyman): Why two tables can't link many-to-many directly, and how an associative (junction) table between them turns it into two one-to-many relationships.

Source: https://www.ask-codey.com/courses/csharp-full-stack-bootcamp/topics/csharp-database-relationships