Siksha Sarovar

Siksha Sarovar (sikshasarovar.com) is a free educational web application that helps students in India learn programming and prepare for academic and competitive exams. The platform offers structured coding courses (C, C++, Python, Java, HTML, CSS, PHP, Power BI, AI, Machine Learning, Data Science), complete university curriculum notes for BCA/MCA students with previous year question papers, Class 10 and Class 12 CBSE/HBSE school notes, and dedicated preparation material for SSC, UPSC, Banking, Railway and other government exams. Browsing the site is completely free and requires no account. Users may optionally sign in with Google solely to save their learning progress, quiz scores and personal preferences across devices.

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Siksha Sarovar is a free e-learning platform for coding courses, BCA university notes and competitive exam preparation. Optional Google sign-in saves your learning progress across devices.

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2.7 What is a Data Model?

Lesson 17 of 62 in the free Power BI notes on Siksha Sarovar, written by Rohit Jangra.

What is a Data Model?

A data model is the foundation of every Power BI report. It defines how your data is structured, organized, and related — enabling efficient analysis and visualization.

Definition

A data model is a structured collection of tables, relationships, and calculations that represents your business data in a way that supports analysis and reporting.

Why Data Modeling Matters

Accuracy: Proper relationships ensure correct calculations across tables • Performance: Well-modeled data loads and queries faster • Usability: A clean model makes it easier to build reports and create measures • Scalability: Good models can accommodate growing data without redesign

Components of a Data Model in Power BI

ComponentDescription
TablesCollections of rows and columns (loaded from data sources)
ColumnsIndividual fields within a table
RelationshipsConnections between tables based on matching columns
MeasuresDAX calculations (e.g., SUM, AVERAGE) that aggregate data
Calculated ColumnsNew columns created using DAX formulas
HierarchiesDrill-down structures (e.g., Year → Quarter → Month)

Fact Tables vs Dimension Tables

Understanding the difference between these two types is fundamental to data modeling.

Fact Tables: • Contain measurable data (numbers, metrics) • Examples: Sales transactions, order details, financial records • Typically large with many rows • Contain foreign keys linking to dimension tables

Dimension Tables: • Contain descriptive data (attributes, labels) • Examples: Products, Customers, Dates, Regions • Typically smaller with fewer rows • Contain primary keys referenced by fact tables

FeatureFact TableDimension Table
ContainsMeasures / NumbersAttributes / Descriptions
SizeLarge (many rows)Small (fewer rows)
KeysForeign keysPrimary keys
ExamplesSales, TransactionsProducts, Customers, Dates
ChangesFrequently updatedRarely changed

The Model View in Power BI

How to Access: • Click the Model View icon on the left sidebar of Power BI Desktop

What You Can Do: • View all tables and their columns • See and manage relationships (lines connecting tables) • Create new relationships by dragging columns • Hide columns from the report view • Organize tables visually on the canvas