DEV Community: FLORENCE MBUTHIA

POWER BI:DATA MODELING

FLORENCE MBUTHIA — Thu, 23 Jul 2026 09:53:59 +0000

Introduction
Power BI is a business intelligence and data visualization tool developed by Microsoft that allows user to connect to multiple data sources, transform and model data, and create reports and dashboards.
In this article we will go through the various types of tables,schemas,data relationships and data models in Power BI.

Lets start with TABLES
To support BI analysis, the data is organised into multiple tables, each serving a specific purpose,ie fact table and dimensional table.
FACT TABLE
The Facts table is the central table in the dataset,stores transaction data and measurable business information.Let's give an example of a dataset that represent information about students,teachers,subjects,
schools, locations,and other related records,making it the larger table that contains all the information in one place.

So the fact table has the following characteristics:

usually has many columns,it combines both:
Descriptive columns - students_name,school_name,assesment_tpye,gender and etc
has numeric columns - numeric values that can be aggregated ie:age, fees, performance_score we can find the SUM,AVERAGE using DAX measures
has repeated values - Country, regions,teachers,schools
has ID columns(which are Foreign keys) - Students id, teachers id,
subject id, school id

foreign keys links fact tables to dimension tables

Fact Table is a central table in a star schema or snowflake schema of a data warehouse.

Dimension Table
Dimension tables help us filter, group, and describe the fact table.
Dimension Table are originally connected to the fact table and it is located at the edge of a star schema or snowflake schema.

The foreign key is mapped to the facts table an example:

From our student data we can create multiple dimensional table that is student table, subject table, school table and others
So the student table will have student id, student name, student region, student age... basically all the student's details needed hence we can say dimensional tables usually answer questions like: Who? What? Where? When? Which category? Which subject?and Which teacher?.

We can be now be able to introduce Schemas after knowing facts and dimensional tables

*Schema Definition *
A schema refers to the overall structure of how tables are organized and related in a data model.
It defines how many tables exist,_ how they connect_, and how data flows between them. The main schema types we are focusing on are:_Star schema Snowflake schema _

Star Schema
A star schema is a data model where you have:One central fact table several dimension tables around it.It is called a star schema because it looks like a** star*. The fact table sits in the middle. The dimension tables surround it.
Star schemas reduce data duplication, improve performance, and make models easier to understand.
**Snowflake Schema*
A snowflake schema is a variation of the star schema where dimension tables are further normalized into additional related tables.
A schema cannot exits without understanding relationships thus we can go through the relationships that exist.

RELATIONSHIPS
Relationships connect fact table to dimensional tables, the fact table is on the many side while dimension tables are on the one side. This relationship turn schemas to a working model
There are keys that help to build a relationships. In this dataset, each dimension table has a primary key ie: Student data has student id, subject table has subject id, school data has school id.

These ids uniquely identify each row in their respective dimension tables and they are called primary key
For example
Subject id should only appear once in the subject id
While a foreign key is the matching key in another table.
For example: fact table [subject id] in the fact table, subject id _can repeat _because one subject can be done many times by different student.

Cardinality
Cardinality describes how rows in one table relate to rows in another table.
The main relationship types are:
One-to-many:
One-to-one
Many-to-many

GIT BASH & GITHUB

FLORENCE MBUTHIA — Fri, 17 Jul 2026 12:32:42 +0000

GIT AND GITHUB
Git is a distributed version control tool that track changes into files or code and we can say it works offline.

A version control is system used to track and manage changes to a remote file in git.

Git Bash is born again shell or basically a command prompt window which emulates UNIX and LINUX environments.

Git hub is a website that stores your Git repositories in the cloud so we can say it exist online.It stores your project's version history online and adds collaboration tools like pull requests, issue tracking, and code review."
_A repository _in GitHub is similar to a folder in your local machine so any changes are tracked.

How to create a repository in GitHub do a simple README.md(markdown) then commit the file and write a massage inside to describe the changes done,then we will need to download a visual code eg VScode where you are able to access the terminals.

Git is used to push changes** to git hub or pull a repo from GitHub**

There are 3 states that every files lives in;

Working Directory-You have made changes but git has not recorded them yet.(it's still on our machine)
Staging Area -You have told Git about the changes. Not saved yet. git add filename thus we git add
Repository (.git)-Changes are permanently saved in history. git commit -m "message"

*Basic Commands/key terms used *

git config allows git to know who you are by using your username and user email e.g. your GitHub account name and email address this is an important info when you want to commit changes as it will tell you who made the changes there are different levels but we will use global Global- applies to all repositories for the current user > Syntax: git config --global user.name or user.email.

-mkdir (make directory) name – creates a new directories for example: my_project in your machine.

-git init this tells Git to start tracking this folder,it initializes git on the folder,the .git folder is where all the history, settings, and saved snapshots lives. It's hidden so you don't accidentally delete it.

-cd moves/change from one directorate to another. cd ~/Downloads

-ls list all the files inside your folder.

-pwd it checks or prints the path of the current working directorate.

-clear clears or removes the display of the terminal window.

-touch creates a file inside a directorate.

We create a README.md file using touch README.md
To know a file is a git repository by default it is called main which happens to be the_ branch assigned_ since you are the creator of the repository.

-echo prints text strings inside the README.md example "hello world"

as it can also be used to write content to a file or create an empty file. To accomplish this, the echo command is utilized in conjunction with single ">" symbol followed by the desired filename we can say then that it can act as a short cut to creating a file.

-git branch list all branches.

-*code * it will open your vs code automatically under the main.py file.

To view the VS code “Hello! World on the terminal/git bash we can use python main.py or py main.py

-git clone downloads a repository that already exists on GitHub to our computers this includes all of the files, branches, and commits. This is done by coping the URL to your git bash.

-git add (the file name) This will add a specific file to the staging area.

-git commit -m ‘’’message’’-used to save the currently staged changes into the local repository and provides a massage that describe the changes made for future reference.

-git status Shows which files are staged and ready to commit

-git pull downloads/update all changes from GitHub(remote repository)into our computer.

-git push origin main pushes the changes(commits) from our local repository to GitHub.

How Excel is Used in Real-World Data Analysis

FLORENCE MBUTHIA — Sun, 07 Jun 2026 04:35:42 +0000

I am currently learning excel one of the most powerful tools for data Analysis and used in all aspect in our world today,I as an accountant I interact with excel every day. But first let's define what is Data, Data Analysis, Excel and then how excel is useful to real world Data analysis.

*What is DATA *
Data is a collection of facts, numbers, words, observations, and any other useful information mostly stored by a computer

It is said Data is everywhere and encountered daily without realizing an example is the number of shirts you own, your name, age and so on, but data by itself may appear meaningless, that's were Data Analysis is introduced

*What is DATA ANALYSIS *
_Data analytics _is the process of collecting, cleaning, transforming, and interpreting data/information for the purpose of studying it to generate insights.
Data analytics as a practice is focused on using tools and techniques to explore and analyze data in real-time or near-real-time to uncover hidden patterns, correlations, and trends. One of the tools available and powerful is EXCEL

*What is EXCEL *
Excel is a microsoft spreedsheet program that organizes data into rows and columns, creating a grid of "cells" used to input, calculate, analyze, and visualize (charts, scatter plots, graphs, and histograms) data/information

Simplifies data handling from basic lists to complex analysis.

*How Excel is used in Real world *

To-Do Lists: Excel allows you to create simple checklists or daily planners to organize tasks and appointments.
Data Tracking: We use Excel to record your daily habits—such as exercise, reading, water intake, or sleep patterns—and even generate charts to visualize your progress over time.
Business and Decision-Making: Organizations analyze data to identify trends, measure performance, and make data driven decisions.
Healthcare organizations: use Excel to manage and analyze patient records and medical data, supporting accurate diagnoses, personalized treatments, disease surveillance, and informed public health decisions.
Finance: Banks and financial institutions use Excel to analyze and visualize financial data, creating structured reports and dashboards that help assess a company's financial performance and support informed business decisions."

*Features /Formulas used in excel: *
Microsoft Excel has a powerful built-in tool called _Power Query _which is ETL (Extract, Transform, Load) that helps users collect, clean, reshape, and combine data from different sources without needing complex formulas or programming.

connect to Multiple Data Sources such as CSV files, Databases and etc.
Clean Data by removing duplicates, handling missing values, Correct data types, conditional formatting, data validation, trim spaces and unwanted characters
Transform Data by filter and sort data, merge columns (Concatenate), Pivot tables and aggregate functions (SUM, AVARAGE, MAX, IF,ETC)

*Conclusion *
> personal reflection
Learning Excel has changed the way I see data by showing me that data is more than just numbers and text—it is valuable information that can be organized, analyzed, and used to make better decisions. Before learning Excel, large amounts of data seemed overwhelming, but Excel has made it easier to manage and interpret information efficiently.
Overall, learning Excel has shown me that it is a powerful and accessible tool that anyone can use to improve their personal, academic, and professional life. Rather than being intimidated by data, I now see it as an opportunity to gain insights and make informed decisions.

DEV Community: FLORENCE MBUTHIA

POWER BI:DATA MODELING

GIT *BASH *& GITHUB

How Excel is Used in Real-World Data Analysis

GIT BASH & GITHUB