How to read from a datbase and edit it

Hello

I've got a problem to see a text read from a database on my local server(xampp).
Here my Code:

$sql = "SELECT text FROM text WHERE id='1'";
$query = mysql_query($sql);
$data = mysql_fetch_array($query);
....
<form method="post" action="insert_into_dtatabase.php?example=true">
   <textarea name="content" cols="50" rows="15" mce_editable="true">
         <?php echo $data[0]; ?>
    </textarea>
   <input type="submit" value="Speichern" />
</form>