MySQL在提交查询 #PHP 时无法识别变量的值

问：

每当我尝试发布MySQL查询时，我都会检索除...这是我在创建一个 HTML 下拉列表后收到的值，该下拉列表在属于当前登录用户的数据库中检索汽车模型。$your_model

如果我在检查查看的“IF”语句之前和之后进行回显，我能够看到......但是一旦我提交或发布我的里程表读数，MySQL就会看到值，值，但看不到值。if(isset($_POST['odo']))$your_model$odo$time$your_model

我尝试在我的代码之前和之后编写那段MySQL代码。我试图将它嵌套到代码中的不同区域，甚至将其嵌套在我执行 if num_of_cars > 0 的地方

我尝试过用引号、单引号、带或不带引号的大括号括起来等$your_model"$your_model"'$your_model'{$your_model}'{$your_model}'

我也尝试过，但不允许MySQL知道变量中的内容'".$your_model."'

我真的尝试了我能想到的一切，并在互联网上搜索。我看到几个论坛有类似的问题......一个没有解决，另一个是通过将大括号包裹在变量周围来解决的，以便MySQL可以识别它。

老实说，我相信这与命令有关......我想知道一旦我提交里程表读数来查询数据库，如果不知何故因为页面刷新，MySQL丢失了变量的值？$_POST$your_model

<?php
        require_once 'header.php';

        if (!$loggedin) die("</div></body></html>");

        if (isset($_GET['view'])) $view = sanitizeString($_GET['view']);
        else $view = $user;

        if ($view != "")
        {
                if ($view == $user) $name1 = $name2 = "Your";
                else
                {
                        $name1 = "<a href='members.php?view=$view'>$view</a>'s";
                        $name2 = "$view's";
                }

                echo "<h4>$name1 Car Portal</h4>";
                showProfile($view);

                echo "<br><br>";

                $car_query = "SELECT model FROM cars WHERE user='$user'";
                $car_result = queryMysql($car_query);
                $num_of_cars = $car_result->num_rows;

                if ($num_of_cars > 0) {
                        while ($row = mysqli_fetch_assoc($car_result)) {
                                $selectedModels[] = $row['model'];
                        }

                }

                if (isset($_POST['selectAModel'])) $your_model = sanitizeString($_POST['selectAModel']);


                echo <<<_END
                        <form method='post' action='car_test.php?view=$view'>
                                <select name="selectAModel">
                                <option value='Select Model'>Select A Model </option>
                _END;
                                foreach($selectedModels as $modelName) {
                                        echo "<option name='$modelName' value='$modelName'> $modelName      </option>";
                                }

                echo <<<_END
                                </select>
                                <input type='submit' name='post_car' value='Submit Car Model'>
                        </form>
                _END;

                echo "<br><br>";
                echo "<div style='text-align:center;'><h3>Your $your_model Odometer Reading</h3></div>";

                if (!isset($_POST['odo']))
                {
                        echo "<span class='info' style='color:red'>You have not entered your $your_model current odometer reading yet</span><br>";
                }

                if (isset($_POST['odo']) && isset($_POST['selectAModel']))
                {
                        $odo = sanitizeString($_POST['odo']);
                        if ($odo != "")
                        {
                                $time = time();
                                queryMysql("UPDATE cars SET odo = '$odo', time = '$time' WHERE user = '$user' AND model = '$your_model'");
                        }

                }

                echo <<<_END
                        <form method='post' action='car_test.php?view=$view'>
                                <input type='text' id='odo' name='odo'>
                                <label for='odo'>Current Odometer Reading</label><br>
                                <input data-transition='slide' type='submit' value='Submit Odometer Reading'>
                        </form>
                _END;

                echo "<br>";

                date_default_timezone_get();

                if (isset($_GET['erase']))
                {
                        $erase = sanitizeString($_GET['erase']);
                        queryMysql("DELETE FROM car WHERE odo='$erase' AND user='$user'");
                }

                $query = "SELECT * FROM car WHERE user='$view' ORDER BY time DESC";
                $result = queryMysql($query);
                $num = $result->num_rows;

                for ($j = 0; $j < $num; ++$j)
                {

                        $row = $result->fetch_array(MYSQLI_ASSOC);

                        if ($row['odo'] != "" && $row['user'] == $user)
                        {
                                echo date('M jS \'y g:ia:', $row['time']);
                                echo "<br><br>";
                                echo "<a href='car.php?view=" . $row['user'] . "'>" . $row['user']. "</a>";
                                echo "<br>";
                                echo "last oil change was at: " . $row['odo'] . "<br>";

                                $current_odo = ((int) $row['odo']);

                                $eight_thousand = 8000;

                                $next_change = $current_odo + $eight_thousand;

                                echo "your next oil change is at: $next_change";

                                if ($row['user'] == $user)
                                        echo "<br><br>[<a href='car.php?view=$view" . "&erase=" . $row['odo'] . "'>erase</a>]";

                                echo "<br><br><br>";
                        }
                }

        }

?>
        </div><br>
        </body>
        </html>