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Types of Relational Models

Depending on the data you're working with, you can set up one of several relational database models. In each of these models, however, you need to differentiate between a child table (also called a dependent table or a controlled table) and a parent table (also called a primary table or a controlling table). The child table is the one that is dependent on the parent table to fill in the definition of its records. The Contacts table, for example, is a child table because it is dependent on the Companies table for the company information associated with each person.

The One-To-Many Model

The most common relational model is one where a single record in the parent table relates to multiple records in the child table. This is called a one-to-many relationship. The sales leads example is a one-to-many relationship because one record in the Companies table can relate to many records in the Contacts table (in other words, you can have multiple sales contacts from the same firm). In these models, the “many” table is the one where you add the foreign key.


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