如果行数超过 15，则 Postman 中不返回 JSON

Question

我有一个 REST API，它是为获取我们正在开发的测验应用程序的问题和答案数据而编写的，并且正在使用的 sql 在 API 文件中如下所示。 我已将限制设置为 (LIMIT 0,15)，就好像我将其更改为 16 一样，邮递员没有返回任何数据。以下是相同的屏幕截图。

<?php

include('config.php');

 if (isset($_SERVER['HTTP_ORIGIN'])) {
    header("Access-Control-Allow-Origin: {$_SERVER['HTTP_ORIGIN']}");
    header('Access-Control-Allow-Credentials: true');
    header('Access-Control-Max-Age: 86400');    // cache for 1 day
}

// Access-Control headers are received during OPTIONS requests
if ($_SERVER['REQUEST_METHOD'] == 'OPTIONS') {

    if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_METHOD']))
        header("Access-Control-Allow-Methods: GET, POST, OPTIONS");         

    if (isset($_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']))
        header("Access-Control-Allow-Headers:
 {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}");

    exit(0);
  }

 $postdata = file_get_contents("php://input");
 if (isset($postdata)) 
 {
    $request = json_decode($postdata);

    $SubID = $request->SubID;

    if( isset($SubID) ) {
        $select_sql = "SELECT * FROM `questions` WHERE `subjectid` = 
   '".$SubID."'";

        $select_query = mysqli_query($con,$select_sql);
        $count = mysqli_num_rows($select_query);
        if($count>0) {
            while($fetch_obj = mysqli_fetch_array($select_query 
 ,MYSQLI_BOTH)) {

                    $SubId = $fetch_obj["subjectid"];
                    $QuestId = $fetch_obj["questionid"];
                    $QuestType = $fetch_obj["questiontype"];
                    $Quest = $fetch_obj["question"];
                    $Ans1 = $fetch_obj["answer1"];
                    $Ans2 = $fetch_obj["answer2"];
                    $Ans3 = $fetch_obj["answer3"];
                    $Ans4 = $fetch_obj["answer4"];
                    $CorrectAns = $fetch_obj["correctanswer"];
                    $Hint = $fetch_obj["hint"];
                    $DiffLevel = $fetch_obj["difficultylevel"];
                    $Status = $fetch_obj["status"];
                    $AnsDescrip = $fetch_obj["ans_description"];

                    $QuestionsList[] = array( "SubjectID" => "$SubId",
                        "QuestionID" => "$QuestId", 
                        "QuestionType" => "$QuestType", 
                        "Question" => "$Quest",
                        "Answer1" => "$Ans1", 
                        "Answer2" => "$Ans2",
                        "Answer3" => "$Ans3",
                        "Answer4" => "$Ans4",
                        "CorrectAnswer" => "$CorrectAns",
                        "Hint" => "$Hint", 
                        "DiffLevel" => "$DiffLevel",
                        "Status" => "$Status",
                        "AnsDescription" => "$AnsDescrip");

            }
                $json = array("status" => 1, 
                    "message" => "Questions list Successfully fetched", 
                    "QuestionsList" => var_dump($QuestionsList));
               /* foreach ($QuestionsList as $value) {
                    print_r($value);
                }*/
        }
        else {
                $json = array("status" => 0, "message" => "No Records 
Found.", "query" => $select_sql);
        }

    }
}
mysqli_close($con);

header('Content-type: application/json');
echo json_encode($json);

?>

在 sql 中有 LIMIT 0, 15 时，它会返回如下所示的数据：

如果我删除 sql 中的 LIMIT，它不会返回任何内容，如下所示。

这是否与 php 中的 JSON 响应数据限制有关，如果是，我在哪里可以更改？而且我还签入了生产实时服务器，它返回了相同的结果。 请帮我解决这个问题。

关于做一个 var_dump($QuestionList) :

Answer 1

您的查询：

$select_sql = "SELECT * FROM `questions` WHERE `subjectid` = 
     '".$SubID."' LIMIT 0, 15";

无限制：

$select_sql = "SELECT * FROM `questions` WHERE `subjectid` = 
     '".$SubID."'";

在LIMIT 0,15:

• 0 是第一行的偏移量。
• 15 是从表返回的最大行数。