Failing in_category or has_category in the_content_feed

$post-ID is not the same as $post->ID. You’re using the former for has_category(), but the latter for get_the_category(). $post->ID is correct.

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