根据基本查询的条件和问题隐藏/显示按钮

Question

我目前正处于社交网站的中期开发阶段。我试图隐藏和显示基于条件设置的按钮，但我之前遇到了困难。目前，我的想法是无法处理如何将其指定为代码。

我有一个Add to Favourites在登录用户的个人资料页面之外的页面上可见。让我们假设我以Freddy身份登录，然后我转到Alice的个人资料页面，其中按钮可见，并且为按钮指定的操作工作，数据被发送到数据库。但是，我试图指定一旦用户已经登录用户收藏夹，Add to Favourites按钮将被Remove from Favourites替换。

我首先无法指定用户只能对用户进行一次收藏，此时，当在任何配置文件上单击Add to Favourites时，数据库将更新为多行，当Freddy应该只允许爱丽丝一次。

这是我目前尝试过的，只允许用户使用一次：

 <?php
// code to process a favourite request
if (isset($_POST['addfriend'])) { 
    $fav_request    = $_POST['addfriend'];
    $favourited_who = $user; // u variable
    $favourited_by  = $username; // logged in user
    /*
    * Need to check that the user who is logged in, hasnt already got the $user in there favs
    */

    // Step 1: Get all the favourites of the logged in user...
    $q = mysqli_query ($connect, "SELECT * FROM favourites");
        while ($r_query = mysqli_fetch_array($q)) {
            $db_fav_who = $r_query['favourited_who'];
            $db_fav_by = $r_query['favourited_by'];
    // Step 2: Check whether the profile page the user is viewing, isnt already in there favourites...



    // Check: See if $user isn't already in there favourites.
    if ($db_fav_by == $username){ // check to see which users favourites we are checking
        // if the user already exists in the logged in users favourites, then display remove from favourites button.
        if ($db_fav_who == $user){
            echo "<div class='edit_profile'>
                <input type='submit' class='btn btn-info' name='remfriend' value='Remove from Favourites'>
            </div";
            }
        }
        }// while loop closed
    if ($user != $username) { // Check: See user isnt favouriting themself.
        $favourite_user = mysqli_query($connect, "INSERT INTO favourites VALUES ('', '$favourited_who', '$favourited_by')");
        echo "done ";
    }
} // if isset closed
?>

目前，有两个按钮在进入任何人（除了你自己的）个人资料页面时都可见：

<div class="edit-profile">
<?php 
    if ($user == $username){
    // dont display buttons
    }else { ?>
        <form action="" method="post">
        <?php
         echo  "
            <input type='submit' class='btn btn-info' name='sendmsg' value='Send Message'/>
            <input type='submit' class='btn btn-info' name='addfriend' value='Add to Favourites'>
        </form>";
    }
    ?> 
</div>

注意：$user是获取网址中u变量的变量。 $username是登录用户的会话变量。

如果{/ 1}}按钮不在登录用户变量中，我怎么才能看到它？如果是，我如何才能看到Add to Favourites按钮而不是Remove from Favourites按钮？