Question

我正在尝试使用while循环外的变量作为要检索的列名

<?php
include 'connection.php';

 $user = "username";
 $data = array();
 $query = mysqli_query($conn, "select `username` from ewallet where `$user` = 'yes'");
 while($result = mysqli_fetch_array($query))
 {
    $data = $result['username']." stat: ".$result['$user']."<br>";
 }
 echo $data;
?>

注意：未定义索引：$ user

Answer 1

也许您可以执行以下操作：

<?php
 include 'connection.php';

 $user = "username";
 $data = array();
 $query = mysqli_query($conn, "select `username` from ewallet where `$user` = 'yes'");
 while($result = mysqli_fetch_array($query))
 {
    $data[] = $result['username']." stat: ".$result[$user]."<br>";
 }
 var_dump($data);
?>

Answer 2

您需要选择两列username和$user。然后，您不应在结果中引用$user。

您应该将$data初始化为字符串，然后使用.=将每一行附加到该行，而不是每次循环都覆盖它。

<?php
include 'connection.php';

 $user = "ian";
 $data = "";
 $query = mysqli_query($conn, "select `username`, `$user` from ewallet where `$user` = 'yes'");
 while($result = mysqli_fetch_array($query))
 {
    $data .= $result['username']." stat: ".$result[$user]."<br>";
 }
 echo $data;
?>

如何在while循环外使用变量

2 个答案: