A friend wants to make a comment on one of my articles, she has to be logged to wordpress?

In wp-admin, Settings » Discussion.

  • [Uncheck] Users must be registered and logged in to comment

Your friend, as well as any anonymous user can post comment now without login.

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