New REDUCE operator can be used in many ways.
DATA: lt_sflight TYPE TABLE OF sflight,
lv_occ_seat TYPE i.
START-OF-SELECTION.
SELECT * FROM sflight INTO TABLE lt_sflight WHERE carrid = 'AA' OR
carrid = 'DL'.
CALL FUNCTION 'REUSE_ALV_GRID_DISPLAY'
EXPORTING
i_callback_program = sy-repid
i_structure_name = 'SFLIGHT'
TABLES
t_outtab = lt_sflight.
lv_occ_seat = REDUCE i( INIT x = 0 FOR ls IN lt_sflight
WHERE ( carrid = 'DL' )
NEXT x = x + ls-seatsocc ).
WRITE:/ 'Total occupied seats for carrid = LH', lv_occ_seat COLOR 3.
OUTPUT
SAPCODES 