$POST和$GET从下拉列表中获取值 - $POST and $GET to get value from dropdown

a.html

function load(str)
{   
    xhttp.open("GET","a.php?q="+str,true);
    xhttp.send();
    }           
}        
<select name = "select"  onchange ="load(this.value)">                   
  <option selected = "selected">Select a movie</option>                   
  <option value= "asc">Name in ascending order</option>
  <option value = "genre">Genre</option>                           
</select>

a.php

$asc = $_POST['asc'];
$genre = $_POST['genre'];
if (!empty($_GET[$asc])) {
    $sql = "SELECT * FROM movies order by Name ASC";
} else if (!empty($_GET[$genre])) {
    $sql = "SELECT * FROM movies order by Genre ASC";
}
$db = mysql_connect("localhost","root","123"); 
$db_select = mysql_select_db('m',$db);
if ( ( $result = mysql_query( $sql, $db ) ) ) {
     echo $result;  
}

我想从下拉按钮中选择值。例如asc，并将该值传递给a.php ($asc = $_POST['asc'])。我怎么能那样做？

<html>
<head></head>
<body>
    <select class="movie" name="select">                   
        <option selected = "selected">Select a movie</option>                   
        <option value= "asc">Name in ascending order</option>
        <option value = "genre">Genre</option>                           
    </select>
        <div class="showMovie"></div>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
    <script>   
        $('.movie').change(function(){
            var movieType= $('.movie').val();
            $.ajax({url:"a.php?movieType="+movieType,cache:false,success:function(result){
                $(".showMovie").html(result);
            }});
        });
    </script>
</body>
</html>

a.php

<?php
$movieType = $_GET['movieType'];
if ($movieType == "asc") {
    $sql = "SELECT * FROM movies order by Name ASC";
} else if ($movieType == "genre") {
    $sql = "SELECT * FROM movies order by Genre ASC";
}
$db = mysql_connect("localhost","root","123"); 
$db_select = mysql_select_db('m',$db);
if (($result = mysql_query($sql, $db))) {
     while($movieName = mysql_fetch_array($result)) {
        echo $movieName['Name']."<br>";
    }
}
?>

使用JS函数，您可以通过"get"方法发送它。所以你有你的价值进入$_GET['q']。。。

如果要执行POST请求，请使用表单或XmlHttp函数：

function load(obj)
{
    var xmlhttp = new XMLHttpRequest();
    xmlxttp.onreadystatechange = function()
    {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200)
        {
            //called when xmlhttp event occurs, here when we receive the response
            console.log(xmlhttp.responseText); //Print the response into the console
        }
    }
    xmlhttp.open("POST", "a.php");
    xmlhttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded'); //we send it as form
    xmlhttp.send(obj.value + "=" + encodeURICompopent(obj.innerHTML));
}

并调用load（this）而不是load（this.value）

在php中，要检查是否发送了值，只需使用isset:

if (isset($_POST['asc'])) //do something;

但我不喜欢这种发送值的方式，这是不推荐的：请求参数名称应该是静态的。。。。

a.html

<script src="//code.jquery.com/jquery-1.11.0.min.js"></script>
<script src="//code.jquery.com/jquery-migrate-1.2.1.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){ 
    $('#select_name').on('change', function() {
        var str = $(this).val();
        $.ajax({
                type: "POST",  
                url: "a.php",  
                data: { q:str},
                success: function(theResponse) {
                    // Output from ajaxpage.php
                    alert(theResponse); // comment this
                    }  
            });
    });
});                 
</script>
<select name = "select_name" id = "select_name">                   
  <option selected = "selected">Select a movie</option>                   
  <option value= "asc">Name in ascending order</option>
  <option value = "genre">Genre</option>                           
</select>

a.php

<?php
$db = mysql_connect("localhost","root","123"); 
$db_select = mysql_select_db('m',$db);
$q   = isset($_POST['q']) ? $_POST['q'] : '';
if ($q == 'asc') 
{
    $sql = "SELECT * FROM movies order by Name ASC";
} 
else if ($q == 'genre') 
{
    $sql = "SELECT * FROM movies order by Genre ASC";
}
else
{
    echo 'Nothing';exit();
}
$qry = mysql_query($sql);
if (mysql_num_rows($qry) > 0)
{
$result = mysql_fetch_object($sql)  ;
echo $result;  
}
?>