无法使用codeigniter 3在SQL中获取具有相同外键的多行

Question

I've created a web app using code igniter 3 to get data from 3 tables and display them in the view (quiz_table,question_table and answers_table). The application is a quiz app(MCQ quiz).

A single quiz contains 4 questions and each question contains 4 answers where only one is correct.

I wrote a SQL query to retrieve data from all 3 tables such as quiz table, creator name, rating, question id, question title, correct answer,and the list of answers for that question. I'm trying to reference the question Id of the answers table and get all 4 answers to a question.

Below is the model code,

function getSingleQuizQuestionDataFromDB($quizId)
{        //insert query
    try {
        $this->db->select('quiz_table.quizName');
        $this->db->select('quiz_table.creatorName');
        $this->db->select('quiz_table.rating');
        $this->db->select('question_table.questionId');
        $this->db->select('question_table.questionTitle');
        $this->db->select('question_table.correctAnswer');
        $this->db->select('answer_table.answer');
        $this->db->from('quiz_table');
        $this->db->where('quiz_table.quizId',$quizId);
        $this->db->join('question_table','question_table.quizId = quiz_table.quizId','INNER');
        $this->db->join('answer_table','answer_table.questionId= question_table.questionId');
        $this->db->group_by(['quiz_table.quizId', 'question_table.questionId']);
        $result = $this->db->get();


        $singleQuizQuestionData= $result->result_array();
        return $singleQuizQuestionData;
    } catch (Exception $e) {
        // log_message('error: ',$e->getMessage());
        return;
    }
}

Below is the result I get from this query,

{
"singleQuizQuestionData": [
  {
     "quizName": "quiz 1",
     "creatorName": "kavibebi",
     "rating": "0",
     "questionId": "76",
     "questionTitle": "q1q1",
     "correctAnswer": "q1a",
     "answer": "q1q1a1"
  },
  {
     "quizName": "quiz 1",
     "creatorName": "kavibebi",
     "rating": "0",
     "questionId": "77",
     "questionTitle": "q1q2",
     "correctAnswer": "q1a",
     "answer": "q1q2a1"
  },
  {
     "quizName": "quiz 1",
     "creatorName": "kavibebi",
     "rating": "0",
     "questionId": "78",
     "questionTitle": "q1q3",
     "correctAnswer": "q1a",
     "answer": "q1q3a1"
  },
  {
     "quizName": "quiz 1",
     "creatorName": "kavibebi",
     "rating": "0",
     "questionId": "79",
     "questionTitle": "q1q4",
     "correctAnswer": "q1a",
     "answer": "q1q4a1"
  }
  ]
  }

As you can see above, this query only returns the first answer from each question.How can I get all 4 answers of a question in the response? Please help!

Answer 1

$singleQuizData = array();
foreach ($singleQuizQuestionData as $row) {
  // If this is the first row for a new question, create a new array for the 
  // question
    $singleQuizData[$row['questionId']] = array(
      'quizName' => $row['quizName'],
      'creatorName' => $row['creatorName'],
      'rating' => $row['rating'],
      'questionId' => $row['questionId'],
      'questionTitle' => $row['questionTitle'],
      'correctAnswer' => $row['correctAnswer'],
      'answers' => $row['answer'],
    );
  }

// The $singleQuizData array should now contain one element for each question