USER EXISTENCE CHECK

***  Check if user exists :

*** BAPI_USER_EXISTENCE_CHECK
  call function 'BAPI_USER_EXISTENCE_CHECK'
    exporting
      username = p_user
    importing
      return   = ls_return.
if ls_return-number = '124'.
" DOES NOT EXISTS
elseif ls_return-number = '088'.
" EXISTS
endif.

*** SUSR_USER_CHECK_EXISTENCE
  call function 'SUSR_USER_CHECK_EXISTENCE'
       exporting
            user_name            = user_name
       exceptions
            user_name_not_exists = 1
            others               = 2.
if sy-subrc EQ 0.
" EXISTS
endif.