PHP 错误消息未显示

Question

所以我正在做一个登录表单，它没有登录，也没有显示错误。 代码如下：

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "studentlogin";
$conn = new mysqli($servername,$username,$password,$dbname);
if($conn->connect_error){
    echo "Connection Failed..//".$conn->connect_error;
}
else{
echo "<br>Connection Established..//";
$loginid = $_POST['id'];
$loginpass = $_POST['loginpass'];
$sql2 = "SELECT LOGINID,PASS FROM EMAIL WHERE LOGINID = '".$loginid."' AND PASS = '".$loginpass."'";
//$sql = "SELECT EMAIL FROM EMAIL WHERE ID = '".$loginid."'";
$result = $conn->query($sql2);
if($result===TRUE){
    $result = $conn->query($sql2);
    if($result->num_rows>0){
        while($row=$result->fetch_assoc()){
            echo "<br>".$row['LOGINID']." welcome to the Student Dashboard..//";
        }
    }
}
else
{
    echo "<br>The Following Error Occured..//";
    echo $conn->error;
}
}
$conn->close();
?>

以下是 output：

Connection Established..//
The Following Error Occured..//

请帮助我已经坚持了两天。

Answer 1

将 mysqli->query() 与 SELECT 语句一起使用会返回 mysqli_result 的实例。 它与 true (=== true) 不同，但也不代表错误。

请观看链接： https://stackoverflow.com/a/34228258/2812447