How to fetch data from MySQL database in JavaScript to build a chart? [closed]

Answer 1

After you have make your select in your DB you have to return the answer in json format (for me I have just make an array with the value to test) :

Your php file (me is serv.php) :

$data = array([1, 19], [2, 11], [3, 14], [4, 16]);
// replace $data by your code to select in DB
echo json_encode($data);

Now you have to get the response in your javascript code. To do that you have to make a "GET" request in javascript or jQuery (jQuery in my case) :

This is your js file :

$.ajax({
   url : 'serv.php', // your php file
   type : 'GET', // type of the HTTP request
   success : function(data){
      var obj = jQuery.parseJSON(data);
      console.log(obj);
   }
});

And in obj you have your data :

So now you have your data and to access, is an array so :

 - obj[0] contains [1, 19], obj[0][0] contains 1 and obj[0][1] contains 19
 - obj[1] contains [2, 11], obj[1][0] contains 2 and obj[1][1] contains 11 ...

In your case, variable1 is the same as obj

Edit With your DB :

Before to send the answer, you have to build correctly your data. So in your case, you have a multidimensional array, that what i make when I push an array in the array named data.

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "datadb";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT column1, column2 FROM chartdata";  //This is where I specify what data to query
$result = mysqli_query($conn, $sql);

$data = array();
while($enr = mysqli_fetch_assoc($result)){
    $a = array($enr['column1'], $enr['column2']);
    array_push($data, $a);
}

echo json_encode($data);