我目前正在使用一个可靠的下拉菜单，该菜单在jQuery和PHP的帮助下运行。正在从MySQL数据库中提取值。php是否有可靠的下拉菜单的选定值？
示例
HTML/PHP
<form action="" method="post">
<select name="gender" id="gender" class="update">
<option value="">Select one</option>
<?php if (!empty($list)) { ?>
<?php foreach($list as $row) { ?>
<option value="<?php echo $row['id']; ?>">
<?php echo $row['name']; ?>
</option>
<?php } ?>
<?php } ?>
</select>
<select name="category" id="category" class="update"
disabled="disabled">
<option value="">----</option>
</select>
<select name="colour" id="colour" class="update"
disabled="disabled">
<option value="">----</option>
</select>
</form>
<select name="gender" id="gender" class="update">
<option value="">Select one</option>
<?php if (!empty($list)) { ?>
<?php foreach($list as $row) { ?>
<option value="<?php echo $row['id']; ?>">
<?php echo $row['name']; ?>
</option>
<?php } ?>
<?php } ?>
</select>
<select name="category" id="category" class="update" disabled="disabled">
<option value="">----</option>
</select>
<select name="colour" id="colour" class="update" disabled="disabled">
<option value="">----</option>
</select>
//jquery code for source list
<script type="text/javascript">
$(document).ready(function(){
$('#gender').change(function() {
if ($(this).val()!='') {
$("#category").load("postfile.php",{gender_id: $(this).val()});
$("#category").removeAttr('disabled');
}
});
//code on change of sel_source
$('#category').change(function() {
if ($(this).val()!='') {
$("#colour").load("postfile.php",{category_id: $(this).val()});
$("#colour").removeAttr('disabled');
}
});
});
</script>
//postfile.php
//your mysql connection other things goes here
//code for category
$objDb = new PDO('mysql:host=localhost;dbname=dbname', 'ur_username', 'ur_password');
if(isset($_REQUEST['gender_id']) && !empty($_REQUEST['gender_id'])) {
$sql = "SELECT * FROM `categories` WHERE `master` = ?";
$statement = $objDb->prepare($sql);
$statement->execute(array($_REQUEST['gender_id']));
$list = $statement->fetchAll(PDO::FETCH_ASSOC);
if(!empty($list)) {
$output = '<option value="">Select</option>';
foreach($list as $row) {
$output .= '<option value="'.$row['id'].'">'.$row['name'].'</option>';
}
} else {
$output = '<option value="">Select</option>';
}
echo $output;
}
//code for color
if(isset($_REQUEST['category_id']) && !empty($_REQUEST['category_id'])) {
$sql = "SELECT * FROM `categories` WHERE `master` = ?";
$statement = $objDb->prepare($sql);
$statement->execute(array($_REQUEST['category_id']));
$list = $statement->fetchAll(PDO::FETCH_ASSOC);
if(!empty($list)) {
$output = '<option value="">Select</option>';
foreach($list as $row) {
$output .= '<option value="'.$row['id'].'">'.$row['name'].'</option>';
}
} else {
$output = '<option value="">Select</option>';
}
echo $output;
}
希望这对你有帮助。
您必须编写一个JavaScript函数，从第一个HTML选择字段中检索所选的值或选项。此函数通常会为当前页面写入一个新的URL路径，并添加一些连接的Get-Variables:
<script type="text/javascript">
getSelectedOptionValue() {
// create some variables to store your know values such as URL path and document
var myPath = " put the URL path to the current document here ";
var currentPage = "currentPage.php";
// get the values of any necessary select fields
var carMake = document.getElementById("carMake").value;
// write out the final URL with the Get Method variables you want using concatnitation
var getMethodURL = myPath + currentPage + "?carMake='" + carMake + "'";
// function refreshes page using the function made URL
window.location.replace( getMethodURL );
}
</script>
由于第二个选择字段依赖于第一个，您必须假设用户将从第一个选项中进行选择。这意味着检索主选择字段值的函数必须运行以响应字段选择的更改。例如
<select name="carMake" id="carMake" onchange="getSelectedOptionValue();">
根据您设置数据库的方式，您可能需要选项标记的值或在选项标记之间提供给用户的字符串。。。这取决于你要记住，如果你的原始记录集还没有提取出写第二组选择选项标签所需的信息，你可以如何重新查询信息。
要使用php写出第二个select字段，只需重复用于第一个字段的while循环。这一次，使用一个变量将您的SQL语句替换为一个新语句，在该变量中，您使用get方法存储了从新URL检索到的值
<?php
// here I am using the more generic request method although you could use the get as well
$carMake = $_REQUEST['carMake'];
sql_secondSelectField = "SELECT * FROM tbl_carModels WHERE carMake = $carMake";
// Run new query and repeat similar while loop used to write your first select field ?>