mysqli_query 有问题，返回 NULL 但查询在 phpmyadmin 中有效

Question

当用户从 iOS 应用程序发送登录命令时，我试图从数据库中检索信息。为了测试这个功能，我手动启动我的 php 页面（例如http://www.testdatabase.com/LoginFunctions.php）并以编程方式强制使用用户名。

问题是 mysqli_query 返回 NULL 值。如果我使用“or die(mysql_error()”，什么也不会发生。即使我使用 mysqli_num_rows 返回 1，但 $result 仍然是空的。所以当 mysql_fetch_assoc 被执行时，程序会崩溃而不显示任何错误。知道吗？谢谢

<?php

    // Create connection

    $con=mysqli_connect("localhost","super","super","testdb");

    // Check connection

    if (mysqli_connect_errno())

    {

        echo "Failed to connect to MySQL: " . mysqli_connect_error();

    }

    $action = "login";

    $username = "Peperoncino";

    $response = array();

    if ($action == "login")

    {

        $query = "SELECT psw AS pswrd,id FROM Activities WHERE nome = 'Peperoncino' LIMIT 1";

        if ($result = mysqli_query($con, $query))

        {

            $values = mysql_fetch_assoc($result);

            $password = $values['pswrd'];

            $response["password"] = $password;

            $response["message"] = "Get information from db";

        }

        else

        {

            echo "err";

        }

        echo json_encode($response);

    }

    // Close connections

    mysqli_close($con);

?>

Answer 1

您正在使用已弃用的 mysql_fetch 函数。使用新的<?php&nbsp; &nbsp; // Create connection&nbsp; &nbsp; $con=mysqli_connect("localhost","super","super","testdb");&nbsp; &nbsp; // Check connection&nbsp; &nbsp; if (mysqli_connect_errno())&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; echo "Failed to connect to MySQL: " . mysqli_connect_error();&nbsp; &nbsp; }&nbsp; &nbsp; $action = "login";&nbsp; &nbsp; $username = "Peperoncino";&nbsp; &nbsp; $response = array();&nbsp; &nbsp; if ($action == "login")&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; $query = "SELECT psw AS pswrd,id FROM Activities WHERE nome = 'Peperoncino' LIMIT 1";&nbsp; &nbsp; &nbsp; &nbsp; if ($result = mysqli_query($con, $query))&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $values = mysqli_fetch_assoc($result);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $password = $values['pswrd'];&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $response["password"] = $password;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $response["message"] = "Get information from db";&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; else&nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; echo&nbsp; mysqli_error($conn);&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; echo json_encode($response);&nbsp; &nbsp; }&nbsp; &nbsp; // Close connections&nbsp; &nbsp; mysqli_close($con);?>