Untitled

//index.php
    <!DOCTYPE html>
    <head>
        <title>Search Products</title>
        <meta charset="UTF-8">
        <script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
    </head>
    <body>
    <?php

    function get_brand(){
        $conn = mysqli_connect('localhost','root','','first_db');

        if(!$conn){
            die('Connection Failed'.mysqli_connect_error());
        }
        require ("dbcon.php");
        $output = '';
        $sql = "SELECT distinct category FROM first_table_1";
        $res = mysqli_query($conn , $sql);
        if(mysqli_num_rows($res)>0){
            while ($row = mysqli_fetch_array($res)) {
                $output .= '<option value="'.$row["category"].'">'.$row["category"].'</option>';
            }
        }
        return $output;

    }

    ?>
    <form action='form.php' method='POST'>
        <div class="container">
            <div class="row">
                <div class="col-lg-4"></div>
                <div class="col-lg-4">
                    <div class="form-group">
                        <label for="brand">Category</label>
                        <select name="brand" id="brand" class="form-control">
                            <option value="">Select category</option>
                            <?php echo get_brand(); ?>
                        </select>
                    </div>
                    <br><br>
                    <div class="form-group">
                        <label for="item">Goods</label>
                        <select name="item" id="item" class="form-control">
                            <option value="">Select goods</option>
                        </select>
                    </div>
                </div>
                <div class="col-lg-4"></div>
            </div>
        </div>
        <input type='submit' name='Send' value='send'>
    </form>


    <script type="text/javascript">
        $(document).ready(function(){
            $('#brand').change(function(){
                var category = $(this).val();
                $.ajax({
                    url: "fetch_model.php",
                    method: "POST",
                    data: {category:category},
                    success:function(data)
                    {
                        $('#item').html(data);
                    }
                });
            });
        });
    </script>
    </body>
    </html>


//fetch_model.php
<?php
    require ("dbcon.php");
    $output = '';
    $sql = "SELECT distinct goodsname FROM first_table_1 WHERE category = '".$_POST["category"]."' ";
    $res = mysqli_query($conn , $sql);
    $output .= '<option value="" disabled selected>Select goods</option>';
    if(mysqli_num_rows($res)>0){
        while ($row = mysqli_fetch_array($res)) {
            $output .= '<option value="'.$row["id"].'">'.$row["goodsname"].'</option>';
        }
    }
    echo $output;
?>


//form.php
<?php
$goodsname = $_POST['item'];
$select = htmlspecialchars ($_POST["item"]);
$dbc = mysqli_connect('localhost', 'root', '', 'first_db') or die ('Error');
echo "goods= ". $select. "<br>";

$query = "SELECT price, count FROM first_table_1 WHERE goodsname = '$goodsname'";
$result = mysqli_query($dbc, $query) or die ('Error');


echo $query."<br>";
if($result)
{
    $rows = mysqli_num_rows($result);

    echo "<table  border='3'><tr></tr>";
    for ($i = 0 ; $i < $rows ; ++$i)
    {
        $row = mysqli_fetch_row($result);
        echo "<tr>";
        for ($j = 0 ; $j < 2 ; ++$j) echo "<td>$row[$j]</td>";
        echo "</tr>";
    }
    echo "</table>";


    mysqli_free_result($result);
}
?>