通过jQuery Ajax读取JSON数据（由PHP创建）导致“parserror”

Question

I create JSON-data with the following php code:

if($res =  $db->query('Select row1 from table1')){
    while($row = $res->fetch_row()){
        $json[] = $row;
    }
}
sort ($json);
$json = json_encode($json);
echo $json;

The result is [["1"],["2"],["3"]].
When I try to fetch this data with jquery ajax

<div id="output">JSON will be put here</div>
<script language="javascript" type="text/javascript">
    $(function ()   {
    $.ajax({
                url: 'json.php',
                dataType: 'json',
                data: '', 
                error: function(request,error) {
                            alert(error);
                            },
                success: function(data) {
                    var json = data[0];
                    alert(json);
                    $('#output').html(json+", ");
                    }
                });
            });

it says: "parseerror".
I searched a lot (here at Stack Overflow), but my jQuery version seem to be right (1.7.2) and reformating the JSON-outpu did not help (I deleted the opening brackets and tried a lot of other things).
Any ideas?

Answer 1

Parse the data return in ajax result,

var retData= JSON.parse(data);