accepted  a correct new bill (control)
REFUSED   status 'washing'
          (CHECK constraint failed: Bill_status_enum)
REFUSED   unknown customer C9999
          (FOREIGN KEY constraint failed)
REFUSED   bill id B99901 (6 characters)
          (CHECK constraint failed: Bill_id_len)
REFUSED   delete service S0001 (has bills)
          (FOREIGN KEY constraint failed)
