mysqli连接文件不识别准备好的语句[重复]

Question

我的 php mysqli 文件出现错误。

致命错误：未捕获的错误：调用成员函数 prepare() on 空入 C:\Users\driek\Desktop\xampp\htdocs\driekvandermeulen.nl_3.0\php\main\contact1.php:20 堆栈跟踪：#0 C:\Users\driek\Desktop\xampp\htdocs\driekvandermeulen.nl_3.0\php\main\contact1.php(33)： writeDatabase('dsgd', 'Lorem@lorem.nl', 'gf', 'awesrdtfgh') #1 {main} 投入 C:\Users\driek\Desktop\xampp\htdocs\driekvandermeulen.nl_3.0\php\main\contact1.php 第 20 行

它没有识别第 20 行的准备语句，但我看不出它有什么问题。

    function dbConnect(){
        $servername = "localhost";                                          // Localhost stays untouched
        $username = "dbUser";                                               // Username of the MySQL database user
        $password = "R4b3Eg5Jt4Y9GKqB";                                         // Password of the MySQL database user
        $conn = new mysqli($servername, $username, $password);                  // Create connection
        if ($conn->connect_error) {                                                 // Check connection
            die("Connection failed: " . $conn->connect_error);
        }
        echo "Connected successfully";
        return;
    }

    function writeDatabase($p_sName,$p_sEmailAddress,$p_sSubject,$p_sMailContent){
       $conn = dbConnect();

    // -------------------- prepare and bind --------------------------------
        //$stmt = $conn->prepare("INSERT INTO `driekvandermeulen.tbl_emailcontacts` (`firstname`, `lastname`, `email`) VALUES (?, ?, ?, ?)");
        $stmt = $conn->prepare();
        $stmt->bind_param($p_sName,$p_sEmailAddress,$p_sSubject,$p_sMailContent);

                $stmt->execute(); // Actual save into the database
    }

Answer 1

dbConnect() 函数没有返回任何内容。因此，将dbConnect() 的结果分配给变量将产生null。

$conn = dbConnect(); 这行将导致$conn = null;。

您应该尝试从dbConnect() 函数返回连接对象：

function dbConnect(){
    $servername = "localhost";                                          // Localhost stays untouched
    $username = "dbUser";                                               // Username of the MySQL database user
    $password = "R4b3Eg5Jt4Y9GKqB";                                         // Password of the MySQL database user
    $conn = new mysqli($servername, $username, $password);                  // Create connection
    if ($conn->connect_error) {                                                 // Check connection
        die("Connection failed: " . $conn->connect_error);
    }
    echo "Connected successfully";
    return $conn;  // <------------------ Check this
}