How to echo PHP array in a format - php

Question

Is there a way I can echo an array of value in this format[200,135,667,333,526,996,564,123,890,464,655] I have my PHP code as below:
$sql_sum_up = "SELECT * FROM `payment`";
$result_sum_up = mysqli_query($conn,$sql_sum_up);
$count_sum_up = mysqli_num_rows($result_sum_up);
while($row_sum_up = mysqli_fetch_array($result_sum_up,MYSQLI_ASSOC)){
$price = $row_sum_up['price'];
}
I want when I echo $price it should come in this format [200,135,667,333,526,996,564,123,890,464,655]

Answer 1

Start of by indenting your code correctly. There's almost always a function for auto-formatting in most editors, such as Visual Studio Code, NetBeans, etc. Or use an online tool to do it.
Correct your SQL query since there's no point getting all values if you just read the price value and you are ordering without mentionning the field name:
SELECT `price` FROM `payment` ORDER BY `field_name` DESC
Create an array variable which you will fill with the prices:
$prices = [];
In your loop reading the database values, fill the array:
$prices[] = $row_sum_up['price'];
Alternatively, you could also fetch all values instead of looping. By the way, it's best to use PHP's PDO abstraction layer instead of mysqli_() functions.
After the loop, export it to JSON:
print json_encode($prices);

Answer 2

first of all, as someone already mentioned in the comments you have an error in your SQL synthax. The correct ORDER BY synthax is "ORDER BY [field-name] DESC"
You could achieve what you want in different ways.
First of all you want to create an array that contains all prices:
$sql_sum_up = "SELECT * FROM `payment`";
$result_sum_up = mysqli_query($conn,$sql_sum_up);
$count_sum_up = mysqli_num_rows($result_sum_up);
$prices = []; //Create the prices array
while($row_sum_up = mysqli_fetch_array($result_sum_up,MYSQLI_ASSOC)){
$prices[] = $row_sum_up['price']; //This pushes every price into the array
}
Make use of join/implode - PHP.net join function
echo '['.join(',',$prices).']';
You could use json_encode function PHP.net json_encode function
echo json_encode($prices);