Modeling data
Modeling is a process of combining multiple data sources and setting relationships between the datasets.
To understand modeling, you need to first grasp some key database terms.
Primary key: The primary key of a relational table uniquely identifies each record in the table (refer to Customers.csv). A table can have only one primary key. Since a primary key is unique, it cannot be repeated in the same table. Take this, for example:
In the preceding example, by specifying the customer ID, I can uniquely identify a person. There can be two customers with the same name, but they will each have a unique customer ID.
Foreign key: A database foreign key is a field in a relational table that matches the primary key column of another table (refer to Product_Sales.csv). See this, for example:
The Customer ID column (used in the earlier example) becomes a foreign key when used in the sales...
