Question

I’m working with three MySQL tables that are related in a PHP application. There are tests which have many questions, and the questions have many answers. What I would like to do is loop through the data as follows:

foreach($tests as $test)
{
    echo $test->testName;

    foreach($test->questions as $question)
    {
        echo $question->questionText;

        foreach($question->answers as $answer)
        {
            echo $answer->answerText;
        }
    }
}

What I would like to know is what the MySQL query and PHP code would be to loop through it in this manner?

edit MySQL can’t return arrays like this, what I should have said is what would the MySQL + PHP code look like.

For clarity, the tables are tests, questions and answers. The questions table contains a test_id column, and the answers contains a question_id

Thanks!

The structure I’m looking to get back would be something along the lines of:

array(
    'testName' = 'Test name string',
    'questions' = array(
        array(
            'questionId' = 1,
            'questionText' = 'Question string',
            'answers' = array(
                array(
                    'answerId' = 1,
                    'answerText' = 'Answer string'
                ),
                array(
                    'answerId' = 2,
                    'answerText' = 'Answer string'
                )
            )
        )
    )
);

edit

My current implementation is as follows, what I wanted to do was eager load the data rather than perform so many queries

$tests = getTests();

foreach($tests as $test){

    $questions = getQuestions($test->id);

    foreach($questions as $question){

        $answers = getAnswers($question->id);

        foreach($answers as $answer){

            // do answer things

        }

    }

}

Answer 1

$mysqli = new mysqli("localhost", "my_user", "my_password", "world");


$query = "SELECT testname, question, answer
    FROM tests 
    JOIN questions ON (tests.id = question.test_id)
    JOIN answers ON (questions.id = answers.id)
    WHERE 'your condition'
    ORDER BY tests.id, question.id"

$result = $mysqli->query($query);

You can use in_array function to get your desired result (you can make array or print result). Here is an example of printing values. (you can use id instead of name for betterment)

$tests_arr = array();
$questions_arr = array();

while( $row = $result->fetch_array(MYSQLI_ASSOC) )
{
    if(!in_array($row['testname'], $test_arr)
    {
        $test_arr[] = $row['testname'];
        echo $row['testname'];
    }

    if(!in_array($result['question'], $question_arr))
    {
        $questions_arr[] = $row['question'];
        echo $row['question'];
    }

    echo $row['answer'];
}