How to delete post comments from the database via SQL statement?

Just run the following commands in your database

DELETE FROM wp_commentmeta;
DELETE FROM wp_comments;

If you changed the db prefix, the name might be foo_comments / foo_commentmeta or similar.

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