AJAX将jQuery发布到PHP $ _POST

I have this modal jQuery AJAX:

        $('#switch_modal').on('show.bs.modal', function (e) {
        var rowid = $(e.relatedTarget).attr('data-id');
            $.ajax({
                type : 'post', // commented for this demo
                url : 'pars.php', // commented for this demo 
                data :  'id='+ rowid,
                success : function(data) {
                $('.fetched-data').show().html(rowid); // show rowid for this demo
                }
            });
        });

My mysql query:

$query="SELECT * FROM games WHERE winner='' ORDER BY amount DESC";
while ($row = $result->fetch_assoc()) {

My modal data-id:

<a href="#viewgame" data-toggle="modal" data-id="<?php echo $row['id'];?>"">

How can i do to use the var rowid like a PHP post? Something like that:

$id = $_POST['rowid'];
echo $id;

If i understand well this test your doing...
Your JavaScript rowid is the value. The $_POST identifier is id.

Try this in your PHP:

$id = $_POST['id'];
echo $id;

You'll get the javascript rowid sent as a POST value (named as $_POST['id']) via ajax...
And returning in data on ajax success.

$('.fetched-data').show().html(data);

So you'll have to use data in your jQuery html()... Wich is the echoed text.

-----
EDIT AFTER ACCEPTATION of this answer
(Based on your last comment)

So i have this query:

$query="SELECT * FROM games WHERE winner='' ORDER BY amount DESC";
if ($result = $conn->query($query)) {
    while ($row = $result->fetch_assoc()) {
        $gameid = $row['id'];
    }
}

So i want to use $gameid variable into this query:

$sql = "SELECT * FROM games WHERE id='".$gameid."'";

I understand, that you want to get THE LAST matching full line where winner value is empty from games table.
No need for an ajax call...
No need for a second query.

Just do it:

$query="SELECT * FROM games WHERE winner='' ORDER BY amount DESC";
$result = $conn->query($query);
$row = $result->fetch_assoc();

for ($i=0;$i<sizeOf($row);$i++){    // This is the «size» (number of values) of one row, the last fetched.
    echo $row[$i] . "<br>";
}

You'll get all your line values echoed...
This will be the LAST matching line fetched.

If you have many matching lines and want all results, do it like this:

$query="SELECT * FROM games WHERE winner='' ORDER BY amount DESC";
$result = $conn->query($query));

while ($row = $result->fetch_assoc()) {     // While fetching, echo all values of one matching line.
    echo "row id: " . $row['id'] . "<br>";
    echo "values: <br>";
    for ($i=0;$i<sizeOf($row);$i++){
        echo $row[$i] . "<br>";
    }
}

Notice that this script, that I suggest, will enlight you about the while fetch loop possible results. You'll have to work a little to have it displayed correctly on your page.
;)