导读：
1. 接口的实现
REPORT z_interface_demo.
interface status.
methods write.
endinterface. "status
class counter definition.
public section.
interfaces status.
methods increment.
private section.
data count type i.
endclass. "counter definition
class counter implementation.
method status~write.
write: / 'count in counter is', count.
endmethod. "status~write
method increment.
add 1 to count.
endmethod. "increment
endclass. "counter implementation
class bicycle definition.
public section.
interfaces status.
methods drive.
private section.
data speed type i.
endclass. "bicycle definition
class bicycle implementation.
method status~write.
write: / 'speed of bicycle is', speed.
endmethod. "status~write
method drive.
add 10 to speed.
endmethod. "drive
endclass. "bicycle implementation
data: count type ref to counter,
bike type ref to bicycle,
status type ref to status, "接口的引用作为工作区
status_tab type table of ref to status.
start-of-selection.
create object: count, bike.
do 5 times.
call method: count->increment,
bike->drive.
enddo.
append: count to status_tab,
bike to status_tab.
loop at status_tab into status.
call method status->write.
endloop.
2. 事件的触发及处理
REPORT z_class_counter_event.
CLASS vehicle DEFINITION INHERITING FROM object.
PUBLIC SECTION.
EVENTS: too_fast.
METHODS: accelerate,
show_speed.
PROTECTED SECTION.
DATA speed TYPE i.
ENDCLASS. "vehicle DEFINITION
CLASS vehicle IMPLEMENTATION.
METHOD accelerate.
speed = speed + 1.
IF speed >5.
RAISE EVENT too_fast.
speed = 5.
ENDIF.
ENDMETHOD. "accelerate
METHOD show_speed.
WRITE: / 'Speed:', speed.
ENDMETHOD. "show_speed
ENDCLASS. "vehicle IMPLEMENTATION
CLASS handler DEFINITION.
PUBLIC SECTION.
METHODS handle_excess FOR EVENT too_fast OF vehicle.
ENDCLASS. "handler DEFINITION
CLASS handler IMPLEMENTATION.
METHOD handle_excess.
WRITE: / 'Speed can not be too fast.'.
* speed = 10.
ENDMETHOD. "handle_excess
ENDCLASS. "handler IMPLEMENTATION
DATA: o_vehicle TYPE REF TO vehicle,
o_handle TYPE REF TO handler.
START-OF-SELECTION.
CREATE OBJECT: o_vehicle, o_handle.
SET HANDLER o_handle->handle_excess FOR ALL INSTANCES.
DO 11 TIMES.
CALL METHOD o_vehicle->accelerate.
CALL METHOD o_vehicle->show_speed.
ENDDO.
3.将数据选择至内表(多行)
DATA: BEGIN OF tab_type,
carrid TYPE spfli-carrid,
connid TYPE spfli-connid,
END OF tab_type.
DATA: spfli_tab1 TYPE TABLE OF spfli,
spfli_tab2 LIKE TABLE OF tab_type.
SELECT *
FROM spfli
INTO TABLE spfli_tab1
WHERE cityfrom = 'NEW YORK' AND cityto = 'LONDON'.
SELECT carrid connid
FROM spfli
INTO CORRESPONDING FIELDS OF TABLE spfli_tab2
WHERE cityfrom = 'NEW YORK' AND cityto = 'FRANKFURT'.
LOOP AT spfli_tab2 INTO tab_type.
WRITE: / tab_type-carrid,
tab_type-connid.
ENDLOOP.
4.动态指定查询条件
DATA: cond(72) TYPE c,
itab LIKE TABLE OF cond,
city1(10) VALUE 'FRANKFURT',
city2(10) VALUE 'NEW YORK',
itab_spfli LIKE TABLE OF spfli WITH HEADER LINE.
CONCATENATE 'CITYFROM = '' city1 '' INTO cond.
APPEND cond TO itab.
CONCATENATE 'OR CITYFROM = '' city2 '' INTO cond.
APPEND cond TO itab.
SELECT *
FROM spfli
INTO TABLE itab_spfli
WHERE (itab).
LOOP AT itab_spfli.
WRITE: /
itab_spfli-cityfrom,
itab_spfli-cityto.
ENDLOOP.
5.多表结合查询-select语句嵌套
DATA: wa_carrid TYPE spfli-carrid,
wa_connid TYPE spfli-connid,
wa_carrname TYPE scarr-carrname.
SELECT carrid connid
FROM spfli
INTO (wa_carrid, wa_connid)
WHERE cityfrom = 'NEW YORK'.
SELECT carrname
FROM scarr
INTO wa_carrname
WHERE carrid = wa_carrid.
WRITE / wa_carrname.
ENDSELECT. "内循环结束
ENDSELECT. "外循环结束
每当在表SPFLI中查询到一个符合条件的carrid值，系统就重新对SCARR进行一次
查询
6.多表结合查询-for all entries
DATA: BEGIN OF wa_spfli,
carrid TYPE spfli-carrid,
connid TYPE spfli-connid,
END OF wa_spfli,
BEGIN OF wa_scarr,
carrid TYPE scarr-carrid,
carrname TYPE scarr-carrname,
END OF wa_scarr,
spfli_tab LIKE TABLE OF wa_spfli.
SELECT carrid connid
FROM spfli
INTO TABLE spfli_tab
WHERE cityfrom = 'NEWYORK'.
SELECT carrid carrname
FROM scarr
INTO wa_scarr FOR ALL ENTRIES IN spfli_tab "比对spfli_tab中的每个元组
WHERE carrid = spfli_tab-carrid.
WRITE / wa_scarr-carrname.
ENDSELECT.
7.组合查询
REPORT Z_SELECT_JOIN.
data: wa_carrid type spfli-carrid,
wa_connid type spfli-connid,
wa_carrname type scarr-carrname.
select spfli~carrid scarr~carrname spfli~connid
from spfli inner join scarr on scarr~carrid = spfli~carrid
into (wa_carrid, wa_carrname, wa_connid)
where spfli~cityfrom = 'NEW YORK'.
write: / wa_carrid, wa_carrname, wa_connid.
endselect.
8.分组总计查询
data: carrid type sflight-carrid,
minimum type p decimals 2,
maximum type p decimals 2.
write: / 'Carrier ID',
at 15 'Minimum Price',
at 30 'Maximum Price'.
select carrid MIN( price ) MAX( price )
into (carrid, minimum, maximum)
from sflight
group by carrid
having MIN( price ) >500
order by carrid descending.
write: / carrid, minimum, maximum.
endselect.