DEV Community: Donnex Okun

Getting Started with Excel for Data Analytics: From Basics to Data Cleaning

Donnex Okun — Wed, 09 Sep 2026 20:24:49 +0000

Introduction to Excel

Data Cleaning is the streamlining of data that is in disarray and poor in quality to make it more digestible for analysis. Excel has features thatv allow you to create reports for intepreting data e.g. Dashboards, Pivot tables amongst others.
Data does not necessarily have to be in numbers, it can also be in text format.

Running Excel

To open excel, go to the search bar, click on it, search Excel. Once highlighted, click on the open icon.
The landing page is made up of three main areas namely:

1.The Home Area: Is the main landing section which allows one to create a new workbook. It also enlists the recently opened files.

The New Area:This is where you get to open a new blank excel file.

The Open Area Allows you to browse from your PC and retrieve any file you may need to upload/open in excel. ** **

When you create a blank workbook, it directs you to the homepage.

Labelling of An Excel Worksheet

The Excel Ribbon: An area that has all the tool bars to be used in excel. It is the section that allows one to access the different tools to be used in excel. For example, the home section of the excel ribbon has different rules for different reasons clustered into: Clipboard;Font;Alignment;Number;Styles;Cells;Editing & Add-Ins.

The Insert section is crucial for reporting especially with the tables and chart icons.

The Draw section presents drawing tools while the Formulas section is a hub of mathematical and text functions.

Under Data section, you can connect your excel to a database and pull data from it. You can also forecast and present case scenarios under What-If Analysis.

Review panel is useful mostly to Informatio Analysts.It has the spelling and grammar checker function that allows for proofreading a dataset. You can also protect sheet to limit the number of viewers/access to the file.

Common Terminologies Associated With Excel

Cell - A single entry box.
Cell Address - A unique identifier of a particular cell.
Name box - This is where a cell address is found. Columns are named alphabetically while Rows are named numerically in excel.
A formula bar is where formulas are written and are always preceded by an equal sign.

Introduction to Excel Cleaning

Dates, Numbers and Boolean data entries are typically aligned to the right whereas text are usually aligned to the left.
Quick Access toolbar contains the icons for un-doing,re-doing and saving.
N/B - Excel does not acknowledge dates outside a conventional calender year.

Range

This is a cell or a group of multiple cells highlighted together on a worksheet. A range doesn't always have to be linear.

Formatting

Transforms the data to make it more professional and presentable. To autofit, go to the Home label on the ribbon, point to the format option and from the dropdown menu select autofit column width.

Wrapping a text

To wrap text in Excel so it fits inside a cell, select the cell and click the Wrap Text button on the Home tab.

Data Validation

Simply refers to conditioning excel to only accept certain prescribed instructions. To validate:

Select the column to validate
Go to the data field of the ribbon
Under data tools, click on the tick icon dropdown menu
Select data validation from the pop-up menu
Under allow, select list from the dropdown menu
Under source, list the column options separated by a comma the press okay.

Once a column is validated, no other entry can be made to a cell within within the column other than the listed options.

Validation can be made for numerical values as well including ranges.

Conditional Formatting

A tool that changes the appearance of cells based on the conditions you define. It does not alter the data itself but how it is presented. It can be used to:

Highlight outliers.
Visualize trends using data bars.
To identify missing information.
To detect patterns.
To improve data readability.

Functions

Functions are built-in formulas used to calculate results automatically. Operators such as Addition, Subtraction, Multiplication, Division, Exponent can be easily performed by these formulas.
Core Statistical and Mathematical Functions:

=SUM: Totals numeric values within a defined range.

=AVERAGE: Determines the arithmetic mean of a dataset.

=MIN/MAX: Ranks the lowest and highest values in a range, highlighting extreme variables.

=MEDIAN: Determines the middle value useful in mitigating the perceptive skew of outliers.

=MODE: States the most frequently occurring value in an array.

=PRODUCT: Multiplies all numbers as given.

=SQRT:Establishes the positive square root of a specific value.

=POWER:Raises a base number to a specified exponential power.

Date and Time Functions

=TODAY(): Displays the current system date, updating automatically realtime.
=NOW(): Generates the exact current date and precise timestamp.
=YEAR(date)/=MONTH(date)/=DAY(date): Extracts the isolated integer value of the year, month, or day from a target date cell.
=DATE(year, month, day): Synthesizes individual year, month, and day integers back into a structured Excel date format.
=NETWORKDAYS(start_date, end_date, [holidays]): Computes the exact number of working days between two dates, automatically excluding weekends and optionally accounting for a custom list of holidays.

Text functions for Data Cleaning

Can be used to eliminate extra spaces in a cell. The find and replace prompt is the most basic and common one however,there exists a plethora of these including:

TRIM: =TRIM(text) removes all leading spaces, trailing spaces, and redundant consecutive spaces from a text string.
LOWER: =LOWER(text) changes every character in a text string into lowercase.
UPPER: =UPPER(text) converts text entirely into uppercase characters.
PROPER: =PROPER(text) creates proper text by capitalizing the first letter of each word and lowering the remaining letters.
LEN: =LEN(text) counts the total character length of a text in a cell including spaces and punctuation. This is highly useful for validating structural lengths like phone numbers or postal codes.
LEFT/RIGHT: = Extracts a specified number of characters starting from the left or right of a cell.
MID: = Extracts a character segment from the middle of a dataset based on a designated starting position and character count.
CONCATENATE/CONCAT:Brings multiple text data cells together into a single, cohesive text block.

Pivot Tables and Charts

A pivot table is basically a summary table which sums large datasets by grouping,counting,averaging or aggregating based on the selected fields. It does not alter the raw data, it only presents it in a different format.It is key to note that the abscence of headers creates breaks.

Creating a Pivot Table

Under the insert icon on the ribbon,click on Pivot Table.
From the dropdown, click on OK to create a New Worksheet.

Rows is for grouping categories, Values is for what is being calculated. Columns is for creating comparative layers or subcategorizing your dataset further.You can drag as many columns into the filter's section to filter a field.

Instead of filters, it is advisable to use Slicers as they are more interactive and visible.

Conclusion

Mastering Excel is a journey that starts from foundational data cleaning to advanced dashboard reporting. As detailed across these modules, data integrity is the bedrock of all reliable analytics. By using text cleaning functions like TRIM, PROPER, and case adjusters, you transform disorganized datasets into accurate, structured information. Implementing strict Data Validation rules protects your workspace from future entry errors, while Conditional Formatting brings key visual patterns and outliers to light without altering the underlying numbers.The true analytical power of Excel emerges when you summarize this clean data using Pivot Tables and Pivot Charts.

Moving beyond traditional dropdown filters to interactive Slicers allows you to build dynamic, presentation-ready dashboards. These tools do more than just summarize rows and columns; they turn raw data into a responsive, visual narrative. With these core skills—from initial cell formatting to multi-table report connections—you can confidently transform complex data environments into clear, actionable business insights.

My First Github Project: From a Local Folder to Github Using Git and SSH

Donnex Okun — Sun, 30 Aug 2026 17:26:06 +0000

Introduction

After so much belabouring which felt like a paralysis analysis, Monday 10th August 2026 marked my formal leap into the vast space of data. In this article, I will share with you my maiden experience in the initial week leading to my first ever GitHub project while recounting each step along the way. We got introduced to platforms such as Dev.to, Markdown, Git and GitHub, Dbeaver, Visual Studio Code, Windows PowerShell, Zoho Cliq, PostgreSQL, Iven amongst other tools. The instructor stressed that the first week would be laidback, focussing more on the installation of requisite tools than active learning. This helped ease some of the tension from those in attendance as there had been plenty of higi haga stemming from the teething challenges of a new cohort.

Introduction to Dev.to

Dev.to was the first to be installed. This is the tool for writing articles and one must therefore setup an account using their Google credentials. One key feature of dev.to is that it stems what you have written to your profile. It also brings together a community of developers with diverse interests and can therefore act as a repository for harnessing theoretical knowledge. The platform has evolved with time to create job opportunities in the form of Technical Writing. Once logged in, navigating through is pretty simple as the user interface mirrors a blend of and social networks.

DEV Challenges

Occasionally, there are tech challenges in the form of mini Hackathons that provide a fun way of building up experience or showcasing learnt skills to the community and even potential employers.

Reading Lists

This is basically an assorted list of articles under your readership.

DEV++ Rewards

This is an incentive program for participating in DEV challenges.

DEV Education Tracks

Curated learning programs balancing between expertise and hands-on experience to come up with practical solutions.
The Dashboard displays account activities over time.

Markdown Language

Is a simple markup language used for text formatting. It switches between two user interfaces, the Edit page where all the primary writing happens and the Preview page that displays the output.
Rules and formatting techniques include:

Titles: Must be short, clear, easily searchable, understandable and properly capitalized.
Headings: Use # for the main heading, ## for subheadings & ### for third-level headings
Paragraph Length: Keep paragraphs concise, ideally 120-150 words to ensure readability.
Styling: Use ** for bold text and _ for italics.
Code Documentation: Use single backticks (or single quotes as specified by the platform) for inline code and triple backticks for blocks of code
Structuring Content: Introductions should begin with a generic, topic related sentence before narrowing down to the article's specific scope. Conclusions are recommended to summarize the technical process.
Other Formatting: Adding cover images (via! and URL links.

PostgreSQL
In day 2, the session started off with downloading and installing PostgreSQL. This is the database management system. A data tools installation guide had been previously shared which eased this process. Alternatively, one can download the tool from their web browser and follow guidelines as stipulated.

Dbeaver
This is an application that allows users to interact with databases more easily. It can therefore be interlinked to various database platforms including PostgreSQL, MySQL, Oracle. etc.
One therefore needs not download all the database platforms but instead can connect them through the cloud using Dbeaver.

Aiven
A cloud data platform through which you can create and manage services including PostgreSQL & MySQL. For our onboarding session, we used the free version which only allows one service to run at a time.

MySQL
Abbreviation for My Structured Query Language, this is a relational database management system that stores, organizes and manages data.

Github
A cloud-based developer platform used to store, manage and share software code. It is advisable to stay professional while setting up your account because it will act as your resume even when seeking opportunities.

Git
A control software system that is designed to manage versions of source code or data. It is capable of handling everything from small to large projects with speed and efficiency. It manages projects on a local host whereas GitHub showcases your projects on a cloud-based environment.

Repository
Sometimes referred to as repo,this is a project being tracked by Git. A GitHub repository is therefore where files and projects are stored with a trail of their historical chronology. Some of the common commands you will come across include:

COMMITwhich is a saved checkpoint in your project's history, is a command issued to permanently save all the data modifications during an ongoing project.
PUSH means sending data from a primary producer system into a database or server without waiting for a request. For example, creating a new user profile or Log In entry.
PULL is the opposite of push and means requesting and retrieving information from a source, such as a database server, an API, or an external file, rather than having that data automatically sent to you. Here, it is the data consumer who initiates the action.
CLONE means to download an existing data repository to your local computer as a Git repository. It allows users to read, write, modify, query and test data without changing the original source.
FORK is to tweak a clone by creating an independent point-in-time copy without affecting the production database.

To check if a tool has been installed on Git bash, the following command applies.
git --version then press enter (where git can be replaced with any other applicable tool)

If the result is a defined version, then the tool is installed if the outcome is otherwise, then the tool is yet to be installed.
To configure your identity, Git will require your name and email address.
N/B: Your email address must match the one used to create your GitHub account.

The commands to use are:
git config --global user.name "Your Full Name" for User Name and
git config --global user.email "Your Email Address" for Email Address
To set Main as the branch, you use:
git config --global init.defaultBranch main then enter.

Once done, you need to verify the configuration through the following commands:
git config --global user.name for User Name
git config --global user.email for Email Address
To get a summary of the three, key in the following command
git config --global --list then press enter

Generating An SSH Key

This is to enable the integration of the GitHub and Git for a seamless integration of the two platforms thereby easing way for the exchange of data. By generating an SSH Key, one bypasses the password and authentication restrictions characteristic of a GitHub account.

First to be generated is your private key which is to be stored in your local computer and must remain confidential.
The second is the public key which will be posted on your GitHub account for public consumption. To generate it, you basically add

pub> to the private key.
Run the following command to establish if it has already been generated.
ls ~al ~/.ssh
If not, run the following command.
ssh-keygen -t ed25519 -C "your_email@example.com"
Then create a passphrase that you will easily recall and confirm.
This should generate and save the keys on your local PC.
The key fingerprint and a random art image will also be generated.
Then rerun the command ls ~al ~/.ssh to regenerate the keys.

Conclusion

In summary, the initial week of data onboarding focused on installing essential development tools, configuring Git and GitHub, and setting up database management systems like PostgreSQL and MySQL. Key practices include utilizing Markdown for documentation, managing local and cloud repositories with Git commands, and establishing secure SSH key integration.