Database Relationships Revisited
As discussed in Chapter 5, databases establish links between records using relation‐ ships. The one-to-many relationship is the most common type of relationship, where a record is linked with a list of related records. To implement this type of relationship, the elements on the “many” side have a foreign key that points to the linked element on the “one” side. The example application in its current state includes two one-to- many relationships: one that links user roles to lists of users and another that links users to the blog posts they authored.