Get fullname from User-id

" ADRP-NAME_FIRST : First name
" ADRP-NAME_LAST  : Last name
" ADRP-NAME_TEXT  : Full name

DATA : lv_usrid     TYPE XUBNAME,
       lv_name_text TYPE ADRP-NAME_TEXT.

" [...]

SELECT SINGLE adrp~name_text INTO lv_name_text
  FROM usr21 JOIN adrp ON usr21~persnumber = adrp~persnumber
                      AND adrp~date_from   = '00010101'
                      AND adrp~nation      = ''
  WHERE usr21~bname = lv_usrid.