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In my SQL hackathon I got the below query, which is asking to display data in a pie chart format.
This is the first time I came across such a query which was challenging and gave me an opportunity to learn something new.
I explored and came with the solution which I would like to share:
QUESTION:
Display a pie chart of gender vs average HbA1c
Before we go into the details, quick check on what is HbA1c:
What is HbA1c?
Hemoglobin (Hb): A protein in red blood cells that carries oxygen throughout the body.
Glycation: The process where glucose (a type of sugar) binds to proteins, including hemoglobin.
HbA1c: The specific form of hemoglobin that glucose has attached to. It reflects the average blood glucose levels over the past two to three months.
How is HbA1c Measured?
Blood Test: The HbA1c test is a simple blood test that measures the percentage of hemoglobin that is glycated.
Reported as a Percentage: The result is given as a percentage. For example, an HbA1c of 7% means that 7% of the hemoglobin is glycated.
Why is HbA1c Important?
Long-term Indicator: Unlike daily blood sugar tests, which only measure blood glucose at a specific moment, the HbA1c test provides an average level over a longer period (2-3 months). This makes it a reliable indicator of overall blood sugar control.
Diagnosis of Diabetes:
Normal: Below 5.7%
Prediabetes: 5.7% to 6.4%
Diabetes: 6.5% or higher on two separate tests
Management of Diabetes: For people already diagnosed with diabetes, the HbA1c test helps in monitoring how well the treatment plan is working. The goal for many people with diabetes is an HbA1c level below 7%.
HbA1c is a critical measure in both the diagnosis and management of diabetes. It offers a longer-term view of blood sugar levels compared to daily blood glucose tests, providing valuable insights into a person's overall blood sugar control and helping to guide treatment decisions.
Now to address this question we came up with the below select query:
Breaking down the query and explaining each statement as follows:
1. Assigning Row Numbers: This is used to assign a unique number to each gender using the ROW_NUMBER() function.
2. Calculating Average HbA1c: Used to calculate the average HbA1c value for each gender using the AVG() function.
3. Calculating Percentage Contribution: Used to calculate the percentage each gender's average HbA1c contributes to the total using the SUM() function.
4. Preparing for Visualization: This converts these percentages into radians for potential use in pie chart plotting.
5. Grouping and Ordering: Data is grouped by gender and ordered by the row numbers assigned initially.
Now coming to the solution for this query, we have several methods in getting the solution in this blog I would be going through the data visualization method in pgAdmin.
To create a pie chart in pgAdmin using the given query, you can follow these detailed steps:
Follow the below sequence of tasks to create the pie chart in pgAdmin using data visualization option:
Step 1. Open pgAdmin and Connect to Your Database:
Launch pgAdmin and connect to your PostgreSQL database.
Step 2. Open the Query Tool:
Navigate to your database in the browser pane, right-click on it, and select `Query Tool`.
Step 3. Execute the Query:
Copy and paste the provided SQL query into the Query Tool:
SELECT
ROW_NUMBER() OVER () AS slice,
gender AS name,
ROUND(AVG(hba1c), 2) AS value,
100.0 * ROUND(AVG(hba1c), 2) / SUM(ROUND(AVG(hba1c), 2)) OVER () AS percentage,
2 PI() SUM(ROUND(AVG(hba1c), 2)) OVER (ROWS UNBOUNDED PRECEDING) / SUM(ROUND(AVG(hba1c), 2)) OVER () AS radians
FROM
demographics
GROUP BY
gender
ORDER BY
1;
Click the `Execute/Refresh` button (lightning bolt icon) to run the query.
Step 4. View Data in Graph Form:
Once the query executes successfully and returns the results, click on the `Graph` button located at the bottom right of the Query Tool's output panel.
Step 5. Select Pie Chart:
In the Graph panel that appears, choose `Pie Chart` from the dropdown menu of available chart types.
Step 6. Configure the Pie Chart:
In the Chart Settings panel:
Label: Set the `Label` field to `name` (this is the gender column).
Value: Set the `Value` field to `value` (this is the average HbA1c value).
Step 7. Generate the Pie Chart:
After configuring the Label and Value fields, the pie chart should be generated automatically, displaying the distribution of average HbA1c values by gender.
Validation:
Ensure your query executes without errors and returns the expected results.
pgAdmin’s charting capabilities are somewhat basic, so for more advanced visualizations, consider using dedicated BI tools like Tableau, Power BI, or Metabase.
Additional Considerations
Data Validation: Ensure your data in the 'demographics' table is accurate and up-to-date. Check for any inconsistencies or missing values that could affect the averages.
Chart Customization: While pgAdmin provides basic charting capabilities, for more advanced features (e.g., interactive charts, better aesthetics), consider exporting the data to tools like Tableau, Power BI, or Python libraries such as Matplotlib or Seaborn.
SQL Performance: If your dataset is large, ensure your SQL query is optimized for performance. Consider indexing columns used in 'GROUP BY' and 'ORDER BY' clauses.
Conclusion:
By following these steps, you should be able to create a pie chart in pgAdmin using the provided query to visualize the average HbA1c values by gender.
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