使用PHP将MySQL表转换为具有子数组的JSON数组

Question

I am currently reading data from a mySQL table in Javascript using PHP's json_encode. My table has this format:

And this structure:

I am using this PHP code to put the into JSON form:

$sql = "SELECT `choice`, `choice_id`, `is_right_choice` FROM Question_choices WHERE `question_id` = 1";
$result = $conn->query($sql);
$rows = array();

if ($result->num_rows > 0) {
while($r = mysqli_fetch_assoc($result)) {
$rows[] = $r;
}} 
else {
echo "Congrats, You Have Displayed All the Answers!";
}

header('Content-Type: application/json');
print json_encode($rows);

When I call this script, I get this result:

[{"choice":"A","choice_id":"1","is_right_choice":"0"},
{"choice":"B","choice_id":"2","is_right_choice":"0"},
{"choice":"Correct","choice_id":"3","is_right_choice":"1"},
{"choice":"D","choice_id":"4","is_right_choice":"0"}]

However, I want to format my JSON so that it has an array of 'question_id' and if you call 'question_id[0] (or 1)', it will have a sub-array in it of all the 'choice' values that also have a 'question_id' of 1.

Ignore the FROM Question_choices WHERE question_id = 1"; , that is just there to get a correct JSON call right now. In the future, my table will have many different values for 'question_id'.

In short, I want to hopefully use PHP's JSON encode to format my JSON like this JSON: {question_id:1{{choice:A},{choice:B}}, question_id:2{{choice:C},{choice:D}}, etc...}

Is this possible using PHP or do I have to look elsewhere?

Answer 1

This will group the choices together for each choice_id :

SELECT GROUP_CONCAT( `choice` ), `choice_id`, `is_right_choice`
FROM Question_choices
GROUP BY `choice`