php - 如何在 PHP MySQLi 中选择多列

Question

我创建了一个表 messages，其中包含 user_id、message_sender、message_receiver、message_receiver_id

查询结果如下

第 1 行:2 abol Alang 3

第 2 行:2 abol mak 4

第 3 行:3 alang abol 2

第 4 行:3 alang mak 4

我想显示所有包含 Alang 记录的查询，即第 1、3、4 行。我设法只显示第 3,4 行但不能显示第 1 行。这是代码

<?php
    include("includes/connections.php");
    function displaymessagesprofile(){
        global $connect;
        global $user_id;

            $get_id      = $_GET['message_receiver_id'];
            $sql_message = "SELECT * FROM messages WHERE user_id='$user_id' OR message_receiver_id='$get_id'";
            $get_message = mysqli_query($connect, $sql_message);

            if($get_message && mysqli_num_rows($get_message) > 0 ){
                while($row_message = mysqli_fetch_array($get_message)){

                $user_id            = $row_message['user_id'];
                $message_sender     = $row_message['message_sender'];
                $message_receiver   = $row_message['message_receiver'];
                $message_receiver_id= $row_message['message_receiver_id'];

                        //to display message sent and received by the user logged in
                        echo    "<div id='message_wrap'>
                                    <p>$message_sender</p>
                                    <p>$message_receiver</p>
                                    <p>$message_receiver_id</p>
                                </div>
                                ";
                }
            mysqli_free_result($get_message);
            }
            else{
                echo "No message yet";
            }
    }
?>

错误如下所示:

Notice: Undefined index: message_receiver_id

Answer 1

$get_id      = $_GET['message_receiver_id'];

change to

$get_id      = isset($_REQUEST['message_receiver_id']) ? $_REQUEST['message_receiver_id'] : '';

您可能需要使用 filter_var sanitizer