How to create bar graphs using complex queries from database dynamically

I am trying to create a bar graph based on the values fetched from database. But the values fetched from database are coming from different tables and minor calculations performed on some of them before plotting a bar graph.

I have written the logic for fetching values and performing calculations in a file known as studenthelp.php. This file contains a link which opens up to another file containing the graph, known as studentgraph.php. And I now want to create a bar graph based on the values retrieved.

For now I have hard coded the values, and a bar graph does come. But I have no idea so as to how to fetch values that I have retrieved in studenthelp.php into this graph file for the graph to be displayed accordingly.

Since I am a novice in PHP I have no idea how to do this. Any suggestions would be appreciated.

You can use GD function of PHP to draw bar graph

You can check this how to create line graph by using data from MySQL table

However a bar graph can be drawn by using image function also by changing height value based on the data. Use one squre image of 3 or 4 pixcel. Then display it like this .

echo "<img src=dot.gif width=3 height=$height>";

Now if you pass the MySQL data to this $height variable then you will have vertical bars representing data of the table.
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