Step 3: Data Modeling Fundamentals

Step 3: Data Modeling Fundamentals

Data modeling is the process of structuring data for ease of use. In analytical systems, we use the Star Schema.

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🏗️ The Star Schema

A Star Schema consists of one Fact Table surrounded by multiple Dimension Tables.

1. Fact Tables

• Store the quantitative data (the “Numbers”).
• Example: Sales_Fact (Quantity, Total Amount, Discount).
• Links to dimensions via Foreign Keys.

2. Dimension Tables

• Store the descriptive data (the “Context”).
• Example: Product_Dim (Name, Color, Category) or Date_Dim.

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📐 Normalization vs. Denormalization

• OLTP (App DBs): Use 3rd Normal Form to reduce redundancy.
• OLAP (Data Warehouses): Use Denormalized Star Schemas to increase query speed.

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🥅 Your Goal

• Draw a Star Schema for a library system (Facts: Book Loans, Dimensions: Books, Users, Dates).
• Understand what a Primary Key and Foreign Key are.