In PHP and jQuery, make one drop-down depend on another drop-down list? [duplicate]

问题

This question already has answers here:

Use jQuery to change a second select list based on the first select list option (7 answers)

How to set values for select box or drop down list box as the previous list box value is set [duplicate] (2 answers)

Closed 6 years ago.

I have two drop down lists one is depended on other if one value selected the other one load same values from database. for example if i select one country other load same cities that country.

<select name="A" class="input_text" id="A">

<?php
include 'config/config.php'; 
$sql="SELECT * FROM department ORDER BY Dept ASC";
$result=mysql_query($sql);$options="";
while ($row=mysql_fetch_array($result)){    
$did=$row["DeptCode"];
$depts=$row["Dept"];
$options.="<OPTION value='$did'>".$depts;}?>
 <option value="0">Select...</option>
<?php echo $options; ?>'
 </option>
</select>

<select name="B" class="input_text" id="B">

<?php           
include 'config/config.php'; 
$sql="SELECT * FROM department WHERE DeptCode=$dpttitle";
$result=mysql_query($sql);$options="";
while ($row=mysql_fetch_array($result)){    
$did=$row["DeptCode"];
$depts=$row["Dept"];
$options.="<OPTION value='$did'>".$depts;}?>
<option value="0">Select...</option>
<?php echo $options; ?>
</option>
</select>

<script type="text/javascript">
A.onblur = function() {
 B.value = this.value;};
</script>

回答1:

You're looking for "ajax" functionality. Try looking into $.get(url,data,success); using JQuery

First, remove dropbox B and replace it with a div with id="B"

$("#A").change(loadCities);
function loadCities(e){
    // prepare get statement
    var url = "http://www.yoursite.com/ajax/getCities";
    var data = {
        country : $("#A").val()
    };
    $.get(url, data, loadCitiesComplete);
}
function loadCitiesComplete(data){
    $("#B").html(data);
}

That url : "http://www.yoursite.com/ajax/getCities" php should look something like

<?
if(isset($_GET['country'])){
    $html = '<select name="B" class="input_text" id="B">';
    include 'config/config.php'; 
    $dpttitle = mysql_real_escape_string($_GET['country']);
    $sql="SELECT * FROM department WHERE DeptCode=$dpttitle";
    $result=mysql_query($sql);$options="";
    while ($row=mysql_fetch_array($result)){    
    $did=$row["DeptCode"];
    $depts=$row["Dept"];
    $html .="<OPTION value='$did'>".$depts;}?>
    $html .= '<option value="0">Select...</option>';
    $html .= '</option>';
    $html .= '</select>';
    echo $html;
}
?>

Obviously the php should use the country $_GET var properly, use PDO or MySQLi with prepared statements for safety, etc. But hopefully this'll get you moving in the right direction.

来源：https://stackoverflow.com/questions/16514594/in-php-and-jquery-make-one-drop-down-depend-on-another-drop-down-list