Valor de lista desplegable dinámico de la base de datos
Cómo puedo conectar el valor de mi menú desplegable principal en un menú desplegable secundario. El valor del menú desplegable es de las tablas main_list y sub_list de la base de datos. Y también la carga del cuerpo no funciona.
Main_list
id | value | id_no
1 | colors | 1
2 | fruits | 2
3 | animals| 3
4 | flowers| 4
sub_list
id | value | category
1 | red | 1
2 | blue | 1
3 | mango | 2
4 | banana | 2
5 | cat | 3
6 | dog | 3
7 | lotus | 4
8 | lily | 4
Y este mi codigo
PHP:
<body onload="run()">
<form id="form1" name="form1" method="post" action="<?php $_SERVER['PHP_SELF']?>">
Drop1
<?php
$mysqli = new mysqli("localhost", "root", "", "lists");
$result = $mysqli->query("SELECT * FROM main_list GROUP BY id ORDER BY id");
$option = '';
while($row = $result->fetch_assoc())
{
$option .= '<option value = "'.$row['value'].'">'.$row['value'].'</option>';
}
?>
<select id="main" name="main" onchange="run()"> <!--Call run() function-->
<option selected=selected>Choose</option>
<?php echo $option; ?>
</select><br><br>
<?php
if (isset($_POST['main'])) {
$mysqli = new mysqli("localhost", "root", "", "lists");
$result1 = $mysqli->query("SELECT * FROM sub_list GROUP BY value ORDER BY id");
$option1 = '';
while($row = $result1->fetch_assoc())
{
$option1 .= '<option value = "'.$row['value'].'">'.$row['value'].'</option>';
}
}
echo 'Drop2 ';
echo '<select name="sub" id="sub" onchange="run()">
<option value=" " disabled="disabled" selected="selected">Choose one</option>';
echo $option1;
echo '</select> ';
?>
<input type="submit" name="submit" value="Submit" />
</form>
Javascript:
<script type="text/javascript">
function run(){
document.getElementById('form1').change()
}
</script>