如何在ComboBox中获取所选值并将其用于第二个ComboBox查询

Question

Here is my Code.

I have several ComboBoxes. I need to get Value from selected in ComboBox and use value in different query. All data I do select from Oracle.

This is my first ComboBox and I need to use VALUE of this ComboBox's option in query of second ComboBox. I mean second ComboBox depends on first select.

How I can get "Value"? I tried to use onchange="this.form.submit()" but it refreshes the page and loses my select. Maybe is it possible to do it with Ajax...

<tr>
    <div class="form-group" style="background-color:#f9f9f9;border:1px solid #ddd;border-radius:4px;padding:2px;">
    <label>Something:</label><span style="color:#FF0000;">*</span></label>
    
        <select class="form-control" input-sm name="example" required>                                    
                                            
            <OPTION VALUE="">Choose any</OPTION>
                                                
            <OPTION VALUE="first">first_name</OPTION>
            <OPTION VALUE="second">second_name</OPTION>
                                        
            </select>
    </div>
</tr>

</div>

Answer 1

I created new php file and name it "js_post.php". When we chose any option from first ComboBox, javascript sending Value to "js_post.php" and there code is cheking Value and depends on Value selecting option.

<?php 
if(isset($_POST["action"]) && $_POST["action"]="get_data" && isset($_POST["muracietnov_id1"]) && $_POST["muracietnov_id1"] !="")
{

    if($_POST["muracietnov_id1"]==1)
    {
        
//```````````````````````HERE SHould be your connection to DB````````````````
$select_query= sqlsrv_query($connection,$query);
                                            
while($result=sqlsrv_fetch_array($select_query)
{
                                            
echo '<OPTION VALUE="'.$result['DATAID'].'">'.$result['NAME'].'</OPTION>';
                                        
}

    }
?>

Here is Javascript and HTML that I used.

$("#muracietnov_id").change(function(){
    var url = 'js_post.php';
    var muracietnov_id=$("#muracietnov_id").val();
    var posting = $.post( url, { 'action': 'get_data','muracietnov_id1': muracietnov_id} );
                    posting.done(function( data ) {
                        //alert(data);
                    $("#muracietnov_id2").html(data);   
                    
        }); 
});

<tr>
    <div class="form-group" style="background-color:#f9f9f9;border:1px solid #ddd;border-radius:4px;padding:2px;">
        <label>Müraciət Növü:</label><span style="color:#FF0000;">*</span></label>
            
            <select class="form-control" input-sm name="muracietnov" id="muracietnov_id" required>';                                      
            
                    <OPTION VALUE="">Seçiminizi edin</OPTION>';
                    
                    <OPTION VALUE="1">Su təchizatı</OPTION>';
                    <OPTION VALUE="2">Kanalizasiya</OPTION>';
                    </select>';
                    </div>
</tr>
            
            
<tr>
    <div class="form-group" style="background-color:#f9f9f9;border:1px solid #ddd;border-radius:4px;padding:2px;">
        <label>Müraciət Səbəbi:</label><span style="color:#FF0000;">*</span></label>
            <select class="form-control" input-sm id="muracietnov_id2" required>
            </select>
    
    </div>
</tr>

</div>