为什么 ajax 请求 PHP 出错

我想在PHP和ajax JQuery中投赞成和不喜欢的投票。

问题是，如果我单击喜欢或不喜欢，则响应中会出现错误。

让我首先向您展示我创建的表查询：

CREATE TABLE IF NOT EXISTS `our_productions` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`title` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`youtube_url` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`like_num` bigint(10) NOT NULL,
`dislike_num` bigint(10) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=3 ;

在这里，我的PHP片段按顺序排列：

数据库.php

<?php
class Tutorial{
    function __construct(){
        //db details
        $db_host = 'localhost';
        $db_user = 'root';
        $db_pass = '123456';
        $db_name = 'productions';
        //connect db
        $con = mysql_connect($db_host, $db_user, $db_pass);
        mysql_set_charset('utf8');
        //select db
        mysql_select_db($db_name, $con);
    }
    function get_rows($id = ''){
        if($id != ''){
            //fetch single row
            $query = mysql_query("SELECT * FROM our_productions WHERE id = $id");
            $data = mysql_fetch_assoc($query);
        }else{
            //fetch all rows
            $query = mysql_query("SELECT * FROM our_productions");
            while($row = mysql_fetch_assoc($query)){
                $data[] = $row;
            }
        }
        return $data;
    }
    function insert($data = array()){
        $data_array_num = count($data);
        $columns = "";
        $values = "";
        $i=0;
        foreach($data as $key=>$val){ 
            $i++;
            $sep = ($i == $data_array_num)?"":", ";
            $columns .= $key.$sep;
            $values .= $val.$sep;
        }
        $insert = mysql_query("INSERT INTO our_productions ($columns) VALUES ($values)");
        return $insert?TRUE:FALSE;
    }
    function update($data = array(), $conditions = array()){
        $data_array_num = count($data);
        $cols_vals = "";
        $condition_str = "";
        $i=0;
        foreach($data as $key=>$val){
            $i++;
            $sep = ($i == $data_array_num)?'':', ';
            $cols_vals .= $key."='".$val."'".$sep;
        }
        foreach($conditions as $key=>$val){
            $i++;
            $sep = ($i == $data_array_num)?"":" AND ";
            $condition_str .= $key."='".$val."'";
        }
        $update = mysql_query("UPDATE our_productions SET $cols_vals WHERE $condition_str");
        return $update?TRUE:FALSE;
    }
}
?>

投票.php

<?php
include_once("db.php");
$tutorial = new Tutorial();
if(isset($_POST['id']) != '' && isset($_POST['type']) != ''){
    //previous tutorial data
    $prev_record = $tutorial->get_rows($_POST['id']);
    //previous total likes
    $prev_like = $prev_record['like_num'];
    //previous total dislikes
    $prev_dislike = $prev_record['dislike_num'];
    //calculates the numbers of like or dislike
    if($_POST['type'] == 1){
        $like = ($prev_like + 1);
        $dislike = $prev_dislike;
        $return_count = $like;
    }else{
        $like = $prev_like;
        $dislike = ($prev_dislike + 1);
        $return_count = $dislike;
    }
    //store update data
    $data = array('like_num'=>$like,'dislike_num'=>$dislike,'modified'=>date("Y-m-d H:i:s"));
    //update condition
    $condition = array('id'=>$_POST['id']);
    //update tutorial like dislike
    $update = $tutorial->update($data,$condition);
    //return like or dislike number if update is successful, otherwise return error
    echo $update?$return_count:'err';
}
?>

最后是指数.php

<?php
    include_once("db.php");
    $tutorial = new Tutorial();
    $trows = $tutorial->get_rows();
?>
<script src="js/jquery-1.11.1.min.js"></script>
<script type="text/javascript">
function voting(id,type,target){
    $.ajax({
        type:'POST',
        url:'votes.php',
        data:'id='+id+'&type='+type,
        success:function(msg){
            if(msg == 'err'){
                alert('Some problem occured, please try again.');
            }else{
                $('#'+target).html(msg);
            }
        }
    });
}
</script>
<?php foreach($trows as $trow){ ?>
    <div id="content" class="full-width flush-top flush-bottom">
        <article class="post-2037 post type-post status-publish format-standard hentry category-aerial category-blog tag-4120 tag-aerial tag-dslr tag-film tag-fortyonetwenty tag-highlight tag-production tag-san-diego tag-video tag-videography tag-vulcan-uav">
            <div class="full-width red timestamp">
                <h2 class="month">Jan</h2>
                <h2 class="year">2016</h2>
            </div>
            <div class="full-width">
                <div class="container">
                    <header>
                        <time class="day"><?php echo $trow['id']; ?></time>
                        <h2 class="post-title"><a><?php echo $trow['title']; ?></a></h2>
                    </header>
                    <div class="entry">
                        <div class="fve-video-wrapper vimeo" style="padding-bottom:56.25%;">
                            <iframe width="560" height="315" src="<?php echo $trow['youtube_url']; ?>" frameborder="0" allowfullscreen></iframe>
                        </div>
                        <p style="text-align: left;">Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
                        tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,
                        quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo
                        consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse
                        cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
                        proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
                    </div>
                    <footer class="social-blog">
                        <!-- Like Icon HTML -->
                        <span class="glyphicon glyphicon-thumbs-up" onClick="voting(<?php echo $trow['id']; ?>,1,'like_count<?php echo $trow['id']; ?>')"></span>&nbsp;
                        <!-- Like Counter -->
                        <span class="counter" id="like_count<?php echo $trow['id']; ?>"><?php echo $trow['like_num']; ?></span>&nbsp;&nbsp;&nbsp;
                        <!-- Dislike Icon HTML -->
                        <span class="glyphicon glyphicon-thumbs-down" onClick="voting(<?php echo $trow['id']; ?>,0,'dislike_count<?php echo $trow['id']; ?>')"></span>&nbsp;
                        <!-- Dislike Counter -->
                        <span class="counter" id="dislike_count<?php echo $trow['id']; ?>"><?php echo $trow['dislike_num']; ?></span>
                    </footer>
                </div>
            </div>
        </article>
    </div>
<?php } ?>

最终，我把一切都安排到位，但在投票时得到错误的回应，请帮助!!