php - 如果行数超过 15，则 Postman 不返回 JSON

Question

我有一个 REST API，用于获取我们正在开发的测验应用程序的问题和答案数据，API 文件中使用的 sql 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， postman 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，它返回如下所示的数据:

如果我删除 sql 中的 LIMIT，它什么都不返回，如下所示。

这是否与 PHP 中的 JSON 响应数据限制有关，如果是，我可以在哪里更改它？而且我也检查了生产实时服务器，它返回了相同的结果。请帮我解决这个问题。

在做一个 var_dump($QuestionList):

Answer 1

您的查询:

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

没有限制:

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

在 LIMIT 0,15 中:

• 0 是第一行的偏移量。
• 15 是从表中返回的最大行数。