Custom signature appears twice on page

You can use get_post_type() to check which content you’re appending your signature to.

function add_signature($content){
    if( get_post_type() == 'post' )
        return $content . "signature";
}
add_filter('the_content', 'add_signature');

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)