问在php中的if条件中发出

EN

<?php
require_once '../../router.php';
require_once '../../'.router('function', 'mini');
require_once '../../'.router('mysql', 'db');
function groups_checker()
{
    if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest')
    {
        if(isset($_GET['grade']))
        {
            global $db;
            $get_groups_select_query = $db->query("SELECT * FROM `groups` WHERE g_grade = '".$_GET['grade']."' ORDER BY `g_max_num` DESC"); // Checking groups existence.
            if(mysqli_num_rows($get_groups_select_query) > 0)
            {
                $get_groups_select_query_fetch = $get_groups_select_query->fetch_array(MYSQLI_ASSOC); // Fetching data after true existence.
                ?>
                <h3>We've found <?= mysqli_num_rows($get_groups_select_query) > 1 ? mysqli_num_rows($get_groups_select_query).' groups ' : ' just a group ' ?> exist, take a look if appropriate. Or <a href="#">Create one?</a></h3>
                <table width="100%" border="1" class="managing_brdr">
                    <tr class="titles_manage_group_main">
                        <td rowspan="2">Group Symbol</td>
                        <td rowspan="2">Group name</td>
                        <td rowspan="2">Group grade</td>
                        <td colspan="4">Appointments</td>
                        <td rowspan="2">Remaining places</td>
                    </tr>
                    <tr class="titles_manage_group_main">
                        <td>First day</td>    
                        <td>Time</td>    
                        <td>Second day</td>    
                        <td>Time</td>    
                    </tr>
                    <tr>
                        <td class="td_centering"><?= $get_groups_select_query_fetch['g_symbol']; ?></td>
                        <td><?= $get_groups_select_query_fetch['g_name']; ?></td>
                        <td class="td_centering"><?= $get_groups_select_query_fetch['g_grade']; ?></td>
                        <td class="td_centering"><?= $get_groups_select_query_fetch['g_fst_day']; ?></td>
                        <td class="td_centering"><?= dateConverter($get_groups_select_query_fetch['g_fst_d_time']); ?></td>
                        <td class="td_centering"><?= $get_groups_select_query_fetch['g_sec_day']; ?></td>
                        <td class="td_centering"><?= dateConverter($get_groups_select_query_fetch['g_sec_d_time']); ?></td>
                        <td class="td_centering">
                        <?php
                        if(empty($get_groups_select_query_fetch['g_max_num']))
                        {
                            ?>
                            It's unlimited. <a href="<?= '../../'.router('sections', 'students').'?action=new_student&steps=second&grade='.$get_groups_select_query_fetch['g_grade'] ?>">Add</a>
                            <?php
                        }
                        elseif(intval($get_groups_select_query_fetch['g_max_num']) > intval($get_groups_select_query_fetch['g_student_number']))
                        {
                            if(intval($get_groups_select_query_fetch['g_max_num']) - intval($get_groups_select_query_fetch['g_student_number']) == 1)
                            {
                                ?>
                                Just 1 place left. <a href="<?= '../../'.router('sections', 'students').'?action=new_student&steps=second&grade='.$get_groups_select_query_fetch['g_grade'] ?>">Add<a>
                                <?php
                            }
                            elseif(intval($get_groups_select_query_fetch['g_max_num']) == intval($get_groups_select_query_fetch['g_student_number'])) // **the issue here.**
                            {
                                ?>
                                It's Full. <a href="">Make an exception</a>
                                <?php
                            }
                            else
                            {
                                echo intval($get_groups_select_query_fetch['g_max_num']) - intval($get_groups_select_query_fetch['g_student_number']) . ' places left. <a href="'.'../../'.router('sections', 'students').'?action=new_student&steps=second&grade='.$get_groups_select_query_fetch['g_grade'].'">Add<a>';
                            }
                        }
                        ?>
                        </td>
                    </tr>    
                <table>
                <?php
            }
            else
            {
                if(!empty($_GET['grade']))
                {
                    alerts('error', 'We didn\'t find any group in '.strtolower($_GET['grade']).', <a href="#">Create one?</a>');
                }
            }
        }
    }
}
groups_checker();
?>