DATA <f> [<length>] <type> [<value>] [<decimals>]
<f>: 变量名称, 最长30个字符, 不可含有 + . , : ( ) 等字符
<length><type>: 数据型态及长度, 如 LINE(20) TYPE C. MYNAME LIKE SY-UNAME.
<value>: 初值
<decimals>: 小数位数

语法：
INCLUDE <程序名>.

语法：
PERFORM <程序名> [USING <传入参数名>] [CHANGING <传出参数名>] [TABLES <内表名>].

语法：
PARAMETERS {para[(len)]}|{para [LENGTH len]}
    [type_options]
    [screen_options]
    [value_options].

SELECT SINGLE * FROM TABLE INTO WA WHERE ID=?.
IF SY-SUBRC = 0.
    ...do something

SELECT SINGLE MATNR ERSDA INTO (GV_MATNR, GV_ERSDA) FROM MARA WHERE ERSDA = '20150701'.

DATA: GS_1 TYPE ZTPX001.

TABLES: ZTPX001.

DATA: BEGIN OF GS_2,
    ZNUMBER LIKE ZTPX001-ZNUMBER,
    ZNAME LIKE ZTPX001-ZNAME,
    END OF  GS_2.

DATA: BEGIN OF GS_3.
DATA:   ZX TYPE C.
        INCLUDE STRUCTURE ZVPX001.
DATA: END OF GS_3.