PHP-JSON中的foreach函数仅返回一行

我正在尝试从JSON响应中显示多于一行,但不知何故每次它仅返回一行.查询在服务器上运行良好.如果我不使用ajax / json使用代码,则代码效果很好.我对此感到头痛.我在这里做错了什么？任何帮助,将不胜感激.

的HTML

         <form>
              <span id="span_section_row"></span>
                    <hr>
                    <div class="row">
                        <div class="form-group col-lg-6">
                            <label for="exam_date">Select Date of Exam</label>
                            <input type="text" class="form-control" id="exam_date" required readonly>
                        </div>
                        <div class="form-group col-lg-6">
                            <label for="exam_time">Enter Exam Time(In Minutes)</label>
                            <input type="number" class="form-control" id="exam_time" required>
                        </div>
                    </div>
                </form>

AJAX通话：

$(document).on('click', '.schedule', function(){
        var exam_id = $(this).attr("id");
        var btn_action = 'fetch_single';
        $.ajax({
            url:'web-services/schedule-exam.PHP',
            method:"POST",
            data:{exam_id:exam_id, btn_action:btn_action},
            dataType:"json",
            success:function(data)
            {
                $('#setup_exam_modal').modal('show');
                $('#span_section_row').html(data.section_row);
            }
        })
    });

PHP：

if($_POST['btn_action'] == 'fetch_single')
    {
        $exam_type_id = $_POST['exam_id'];
        $query = "
        SELECT a.*, b.exam_type_name 
                        FROM exam_section a
                        INNER JOIN exam_type b 
                        ON a.exam_type_id=b.exam_type_id
                         WHERE a.status = :status
                         AND a.exam_type_id = :exam_type_id
        ";
        $statement = $conn->prepare($query);
        $statement->execute(
            array(
                ':status'    =>    'active',
                ':exam_type_id'    =>    $exam_type_id

            )
        );
        $result = $statement->fetchAll();
        foreach($result as $row)
        {
            $output['section_id'] = $row['section_id'];
            $output['exam_type_id'] = $row['exam_type_id'];
            $output['section_name'] = $row['section_name'];
            $output['exam_type_name'] = $row['exam_type_name'];

            $output['section_row'] = 
                                '<div class="row">
                                <div class="form-group col-lg-4">
                                    <label for="select_section"></label>
                                    <p id="select_section">'.$row['section_name'].'</p>
                                </div>
                                <div class="form-group col-lg-4">
                                    <label for="no_of_questions">No. of Questions</label>
                                    <input type="number" class="form-control" id="no_of_questions" required>
                                </div>
                                <div class="form-group col-lg-4">
                                    <label for="mark_per_question">Mark Per Question</label>
                                    <input type="number" class="form-control" id="mark_per_question" required>
                                </div>
                            </div>
                            ';
        }
        echo json_encode($output);
    } 

解决方法:

首先,在PHP中,每次循环时都要覆盖数组,因此只有一次出现回传给javascript处理

if($_POST['btn_action'] == 'fetch_single') {
    $exam_type_id = $_POST['exam_id'];
    $query = "SELECT a.*, b.exam_type_name 
              FROM exam_section a
                INNER JOIN exam_type b ON a.exam_type_id=b.exam_type_id
              WHERE a.status = :status
              AND a.exam_type_id = :exam_type_id";

    $statement = $conn->prepare($query);
    $statement->execute(
            array(  ':status' => 'active', 
                    ':exam_type_id' => $exam_type_id)
                );
    $result = $statement->fetchAll();

    foreach($result as $row) {
        $htm = '<div class="row">
                    <div class="form-group col-lg-4">
                        <label for="select_section"></label>
                        <p id="select_section">'.$row['section_name'].'
                        </p>
                    </div>
                    <div class="form-group col-lg-4">
                        <label for="no_of_questions">No. of Questions</label>
                        <input type="number" class="form-control" id="no_of_questions" required>
                    </div>
                    <div class="form-group col-lg-4">
                        <label for="mark_per_question">Mark Per Question</label>
                        <input type="number" class="form-control" id="mark_per_question" required>
                    </div>
                </div>';

        $output[] = [
                    'section_id'        => $row['section_id'],
                    'exam_type_id'      => $row['exam_type_id'],
                    'section_name'      => $row['section_name'],
                    'exam_type_name'    => $row['exam_type_name'],
                    'section_row'       => $htm
                    ];
    }
    echo json_encode($output);
} 

所以现在在JavaScript中,您将需要按照RASHAN的建议处理该数组

$(document).on('click', '.schedule', function(){
    var exam_id = $(this).attr("id");
    var btn_action = 'fetch_single';
    $.ajax({
        url:'web-services/schedule-exam.PHP',
        method:"POST",
        data:{exam_id:exam_id, btn_action:btn_action},
        dataType:"json",
        success:function(data)
        {
            $('#setup_exam_modal').modal('show');
            //$('#span_section_row').html(data.section_row);
            var t="";
            $.each(data,function(index,value){
               // concatenate all the occurances of the html and place on page
                t += value.section_row;
            })
            $('#span_section_row').html(t);
        }
    })
});

Now you have one remaining problem that I can see and that is you are generating multiple HTML element all with the same id like here,

<p id="select_section">'.$row['section_name'].'

in multiple sections of your HTML. As I am not familiar with whats going on elsewhere in the code, possibly you dont need these id‘s at all and can remove them. Or you will have to make them unique on the page, or amend your javascript to select those elements some other way