Is there anything special I have to think of when setting post_date_gmt when inserting a new post?

Most of the times, you can just leave it empty and the wp_insert_post will take care of handling it but if you want to set it use php’s function:

gmdate("Y-m-d h:m:s", strtotime($current_user->user_registered))

which works exactly like the php date function.

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