Donut chart by selecting data from MySQL database using PHP Script

File Name	Details
config.php	MySQLi Database connection details are stored here.
sql_dump.txt	SQL Dump to create chart_data table with sample data.
readme.txt	Instructions on how to run the script
index.php	The main file to display records and the Pie chart.

Download Zip file at end of this tutorial.

1 : Collecting data from MySQL database

After connecting to database through config.php file, we will run the SQL to collect the data from MySQL table. You can read more on MySQLi and how to collect data from table.

if($stmt = $connection->query("SELECT language, nos  FROM chart_data")){

  echo "No of records : ".$stmt->num_rows."<br>";
$php_data_array = Array(); // create PHP array
  echo "<table>
<tr> <th>Language</th><th>Nos</th></tr>";
while ($row = $stmt->fetch_row()) {
   echo "<tr><td>$row[0]</td><td>$row[1]</td></tr>";
   $php_data_array[] = $row; // Adding to array
   }
echo "</table>";
}else{
echo $connection->error;
}

2 : Data array in PHP

Before displaying records in a table we have created an array in PHP ( $php_data_array). While displaying the records in a table we store each record inside the PHP array.

$php_data_array[] = $row; // Adding to array

After displaying all the records in a table we have the $php_data_array with all the data collected from MySQL table. We can display the Json string like this.

echo json_encode($php_data_array);

3 : Transferring data from PHP to JavaScript to crate the chart

By using json_encode we will create an json string which can be used to create the JavaScript two dimensional array.

echo "<script>
        var my_2d = ".json_encode($php_data_array)."
</script>";

4 : Adding data to Chart

Our JavaScript array my_2d stores all the data required for creating the chart. We need to display them in the format required by our Chart library.

for(i = 0; i < my_2d.length; i++)
    data.addRow([my_2d[i][0], parseInt(my_2d[i][1])]);

We used parseInt() function to convert input string value to Integer. JavaScript part is here .

<script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>
<script>
  google.charts.load('current', {'packages':['corechart']});
     // Draw the pie chart when Charts is loaded.
      google.charts.setOnLoadCallback(draw_my_chart);
      // Callback that draws the pie chart
      function draw_my_chart() {
        // Create the data table .
        var data = new google.visualization.DataTable();
        data.addColumn('string', 'language');
        data.addColumn('number', 'Nos');
		for(i = 0; i < my_2d.length; i++)
    data.addRow([my_2d[i][0], parseInt(my_2d[i][1])]);
// above row adds the JavaScript two dimensional array data into required chart format
    var options = {title:'plus2net.com : How the tutorials are distributed',
	pieHole: 0.5,
	'width':600,
	'height':500,			   
		};

        // Instantiate and draw the chart
        var chart = new google.visualization.PieChart(document.getElementById('donutchart'));
        chart.draw(data, options);
      }
</script>

5. HTML part

We can show the chart inside a <DIV> tag and place the same any where we want to display the chart.

<div id="donutchart"></div>

The chart drawn above can be displayed with live internet connection as the library is to be loaded from gstatic.com

Data is collected from MySQL database table so data can be edited by using script and the same will be reflected by the Chart. We have not included this part in the present script and there are many tutorials available here one handling data using PHP and MySQL.

You can read tutorials on other types of charts displayed by using data from database. 3D Pie Chart with change in data Understanding different types of Charts
Chart Basics

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Donut Chart using data from MySQL table by PHP

1 : Collecting data from MySQL database

2 : Data array in PHP

3 : Transferring data from PHP to JavaScript to crate the chart

4 : Adding data to Chart

5. HTML part

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