Don';当我单击select form=“id=undefined”时,t显示信息


Don't show information when i click select form = “id=undefined”

请帮帮我。。当我选择表单时,它显示"select_modelcar.php?brandid=undefined",但我试图将此代码粘贴到url中并定义id"select_modelcar.php?brandid=40",结果如下。我想以选择的形式选择相同的类别,比如当我选择"丰田"品牌时,它会显示丰田品牌的所有车型(凯美瑞、雅力士等)。

当我单击"选择表单">>

在此处输入图像描述

url中的过去并定义id>>

在此处输入图像描述

select_brandcar.php

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
</head>
<?php $servername = "localhost";
$username = "root";
$password = "usbw";
mysql_connect($servername,$username,$password);
mysql_select_db("carspecth");
 ?>
 
<body>
<script>
 function ValueID(){
     document.getElementById("getval").innerHTML = ('select_modelcar.php?brandid='+this.value);;
 };
</script>
    <select name="select_brandcar" id="select_brandcar" onclick="ValueID();" >
    <option>Press Choose</option>
    <?php 
  	$sql = sprintf ("SELECT * FROM brand" );
   	$res = mysql_query ($sql);
  	while ($arr = mysql_fetch_array($res)){
	printf ("<option value='%s'>%s</option>" ,$arr['brandid'], $arr['brandname']);
	}
   ?>
<span id="getval"></span>
</body>
</html>

select_modelcar.php

<?php
mysql_query("SET NAMES UTF8");
include 'include_connectdb.php';
@$varbrandid = $_GET['brandid'];
@$sql = sprintf("SELECT * FROM maingeneration WHERE brandfk = %s", $varbrandid);
/*id ของตาราง catagory*/
@$res = mysql_query($sql);
printf("<select name='select' id='select'>");
while ($arr = mysql_fetch_array($res)) {
    printf("<option value='%s'>%s</option>", $arr['maingenerationid'], $arr['maingenerationname']);
}
printf("</select>");
?>

谢谢。。。。。。。。。。。!

        Please use onchange event instead of onclick and pass the value in the ValueID function.
        Please replace javascript and php code with this:
            <script>
     function ValueID(vid){
        $.ajax({
                    url: 'select_modelcar.php?brandid='+vid,              
                    type: 'POST',
                    success: function (data) {
                        if (data === 'success') {
                           document.getElementById("getval").innerHTML = data;
                        }
                    }
                });  
     };
    </script>
                <select name="select_brandcar" id="select_brandcar" onchange="ValueID(this.value);" >
                <option>Press Choose</option>
                <?php 
                $sql = sprintf ("SELECT * FROM brand" );
                $res = mysql_query ($sql);
                while ($arr = mysql_fetch_array($res)){
                   printf ("<option value='%s'>%s</option>" ,$arr['id'], $arr['name']);
                 }
               ?>
            <span id="getval"></span>

In PHP FIle:
<?php
mysql_query("SET NAMES UTF8");
include 'include_connectdb.php';
@$varbrandid = $_GET['brandid'];
@$sql = sprintf("SELECT * FROM maingeneration WHERE brandfk = %s", $varbrandid);
/*id ของตาราง catagory*/
@$res = mysql_query($sql);
$select = "<select name='select' id='select'>");
while ($arr = mysql_fetch_array($res)) {
    $select .= printf("<option value='%s'>%s</option>", $arr['maingenerationid'], $arr['maingenerationname']);
}
$select .="</select>";
echo $select;
exit;
?>

试试这个:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script>
</head>
<?php $servername = "localhost";
$username = "root";
$password = "usbw";
mysql_connect($servername,$username,$password);
mysql_select_db("carspecth");
 ?>
 
<body>
<script>
 function ValueID(element){
     document.getElementById("getval").innerHTML = ('select_modelcar.php?brandid='+element.value);;
 };
</script>
    <select name="select_brandcar" id="select_brandcar" onclick="ValueID(this);" >
    <option>Press Choose</option>
    <?php 
  	$sql = sprintf ("SELECT * FROM brand" );
   	$res = mysql_query ($sql);
  	while ($arr = mysql_fetch_array($res)){
	printf ("<option value='%s'>%s</option>" ,$arr['brandid'], $arr['brandname']);
	}
   ?>
</select>
<span id="getval"></span>
</body>
</html>