PHP：基于下拉列表的 MySQL 值调用

Question

所以我想做的是从我的服务器调用一个值，并根据我从下拉框中选择的内容将其输入到一个变量中，然后我想获取这些变量并通过 javascript 计算一个新的输出（我不认为我在最后一部分需要帮助，但我喜欢提前）。无论如何，这是代码

$db_name = 'prod_chrotex_db';
$conn = new mysqli($host, $user, $pass, $db_name);
$query = mysqli_query($conn, "SELECT * FROM table1 INNER JOIN table2 ON id ");

echo '<select name="TITLE">';
while ($row = mysqli_fetch_array($query)) {
    echo '<option value="' . $row['title']  . '">' . $row['title'] . '</option>';
    $rows = mysqli_fetch_assoc($query);
    echo 'ID: ' . $rows['ID'] ;
    $value = $rows['values']
};

echo "</select>";

Answer 1

$db_name = 'prod_chrotex_db';
$conn = new mysqli($host, $user, $pass, $db_name);
$query = mysqli_query($conn, "SELECT * FROM table1 INNER JOIN table2 ON id ");

echo '<select name="TITLE"  id="selectb" onchange="callfunction();>';
while ($row = mysqli_fetch_array($query)) {
    echo '<option value="' . $rows['ID'] . '" ">' . $row['title'] . '</option>';


};

echo "</select>";

?>
<script>

    function callfunction(){
        var val = document.getElementById('selectb').value();
        // You get the selected value in val variable. Here you can calculate what you want

        }

</script>