PHP - 在while循环中没有显示mysqli_fetch_assoc的任何内容(PHP - doesn`t show anything with mysqli_fetch_assoc in while-loop)

 我想通过JSON将MySQL数据库中的一些数据提供给Android应用程序。 
 
 到目前为止，我已经编写了这个PHP脚本来给我JSON对象： 
 
$result = mysqli_query($con,"SELECT * FROM job");

$row = mysqli_fetch_assoc($result); 

while($row = mysqli_fetch_assoc($result)){
  $output[] = $row;
}

print(json_encode($output));
 
 我偶然发现当我不添加“$ row = mysqli_fetch_assoc（$ result）;”这一行时 在while循环之前，它不返回任何东西。 但是当我在示例中添加此行时，JSON对象不包含第一个元素。 
 
 我相信它因为这行$ row已经包含第一行。 
 
 希望你能帮助我:) 

I want to give some data from a MySQL database to a Android App via JSON.
 
So far i have written this php script to give me the JSON object:
 
$result = mysqli_query($con,"SELECT * FROM job");

$row = mysqli_fetch_assoc($result); 

while($row = mysqli_fetch_assoc($result)){
  $output[] = $row;
}

print(json_encode($output));
 
I have found out by accident that when I dont add the line "$row = mysqli_fetch_assoc($result);" before the while-loop it doesn`t return anything. But when I do add this line like in the example the JSON object doesnt contain the first element.
 
I believe its because of this line where $row already contains the first line.
 
Hopefully you can help me :)

原文：https://stackoverflow.com/questions/40164367