link to a random custom post while excluding current post

On your argument, exclude the current post using post__not_in

$args=array(
    'post_type'=>'projects', 
    'orderby'=>'rand', 
    'posts_per_page'=>'1', 
    'post__not_in'=> array( get_the_ID() )
);

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