PHP 从两个表中搜索

Question

我在 PHP/MySQL 中有一个搜索功能，只要我只从一张表中搜索，它就可以正常工作。问题是我需要搜索一个表并显示其中的信息，同时还显示另一个表中的两个部分。使用此代码我收到一个 Notice: Trying to get property of non-obect 错误。我的 PHP 代码是这样的:

if(isset($_GET['search'])) {
    $search = $link->escape_string($_GET['search']);
    $query = $link->query("SELECT l.Id, l.ImageId, l.Subject, l.Level, l.Aim, i.NameImg, i.AltImg FROM LessonPlans l, Images i WHERE Subject LIKE '%".$search."%' OR Level LIKE '%".$search."%' OR Aim LIKE '%".$search."%' AND Language='English'");

if($query->num_rows){        
    while($r = $query->fetch_object()){

    echo '<div class="col s6 m4 l3">
            <div class="card">
                <div class="card-image waves-effect waves-block waves-light">
                    <img class="activator" src="../mlslp/assets/img/'.$r->NameImg.'" alt="'. $r->AltImg.'">
                </div>
                <div class="card-content">
                    <span class="card-title activator grey-text text-darken-4 truncate tooltipped" data-position="bottom" data-delay="800" data-tooltip="'.$r->Subject.'">'.$r->Subject.'</span>
                    <p class="blue-text">'.$r->Level.'</p>
                </div>
                <div class="card-action">
                    <a href="lessonplan.php?Id='.$r->Id.'">Open Lesson Plan</a>
                </div>
                <div class="card-reveal">
                    <span class="card-title grey-text text-darken-4">'.$r->Subject.'<i class="material-icons right">close</i></span>
                    <p>'.$r->Aim.'</p>
                </div>
            </div>
        </div>';

        }
    } 
}

有没有办法解决两个表不发送对象的问题？我不确定是查询错误还是 if/while 语句错误。

Answer 1

如果两个表具有相同的名称 ImageId，则尝试 beloq 查询

$query = $link->query("SELECT l.Id, l.ImageId, l.Subject, l.Level, l.Aim, i.NameImg, i.AltImg FROM LessonPlans l join Images i on i.ImageId=l.ImageId WHERE Subject LIKE '%".$search."%' OR Level LIKE '%".$search."%' OR Aim LIKE '%".$search."%' AND Language='English'");

i.ImageId -> Image id of table Images table

l.ImageId -> Image id of LessonPlans table