Covid Dashboard- Tableau, SQL Server Studio

Project Overview

When the pandemic hit, the sheer volume of global health data was overwhelming. For this project, I wanted to take those massive, complex datasets and turn them into a clear visual story. I built a data pipeline using SQL Server to clean and transform raw global health data, and then used Tableau to build an interactive, user-friendly dashboard that tracks infections, mortality rates, and vaccine rollouts worldwide.

Link to Dashboard: Tableau

The Technical Deep Dive (SQL)

Before creating any charts, I needed to make sure the data was accurate and structured correctly. The raw data had a few quirks, so I used SQL to clean it up and prep it for visualization.

Overcoming Data Challenges

• Fixing Double-Counting Errors: Early on, I noticed that monthly totals were compounding incorrectly because of how the raw rows were aggregated. I refactored my equations—shifting to a precise SUM(new cases) / MAX(population) approach—to ensure each wave of the pandemic was captured accurately month-by-month without inflating the numbers.

• Tracking Rolling Totals with CTEs: To see how fast vaccines were being distributed, I needed to calculate a running total over time. Because you can't easily perform math on a running total in a basic query, I used a Common Table Expression (CTE) and Window Functions to isolate the rolling sums and cleanly calculate the percentage of the population vaccinated.

• Optimizing for Tableau: To keep the final dashboard lightweight and fast, I saved my optimized queries into structured Database Views. This meant Tableau didn't have to do the heavy lifting or recalculate complex math on the fly.

• Filtering Redundancies: In my final queries, I explicitly filtered out overlapping regions like 'World' and 'European Union' to prevent countries from being counted twice on the same chart.

What the Dashboard Represents (Tableau)

The final Tableau dashboard is broken down into four key areas, designed to give users both a high-level overview and a detailed look at the data:

1. The Global Snapshot (KPIs): Right at the top, you can see the absolute scale of the pandemic—total global cases, total deaths, and the overall global mortality rate.

2. Continental Breakdown (Bar Chart): A clean comparison showing which continents suffered the highest total death counts, keeping the data apples-to-apples by removing regional duplicates.

3. Global Hotspots (Interactive Map): A color-coded world map that visualizes infection rates as a percentage of each country's population. This makes it easy to spot which nations were hit hardest relative to their size.

4. Pandemic Waves Over Time (Line Graph): A time-series chart that lets you track how the virus spread chronologically, showing how different countries peaked at different times.