ABAP DESCRIBE语句

声明：原创作品，转载时请注明文章来自SAP师太技术博客（博/客/园ｗｗｗ.ｃｎｂｌｏｇｓ.ｃｏｍ）：www.cnblogs.com/jiangzhengjun，并以超链接形式标明文章原始出处，否则将追究法律责任！原文链接：http://www.cnblogs.com/jiangzhengjun/p/4292805.html

DESCRIBE DISTANCE

DESCRIBE

可参考反射RTTS

DESCRIBE FIELD

DESCRIBE FIELD dobj
[TYPE typ [COMPONENTScom]]
[LENGTHilen IN {BYTE|CHARACTER} MODE]
[DECIMALSdec]
[OUTPUT-LENGTH olen]
[HELP-ID hlp]
[EDIT MASK mask].

TYPE typ

以下是不同类型的dobj返回的类型ID列表，ID大小写敏感：

Numeric Data Type	ID
b	b
s	s
i	I
p	P
decfloat16	a
decfloat34	e
f	F

Character-Like Data Type	ID
c	C
string	g
n	N
d	D
t	T

Byte-Like Data Type	ID
x	X
xstring	y

Reference Type	ID
Data reference	l
Object reference	r

Complex Type	ID
Flat structure	u
Deep structure	v
Internal table	h

COMPONENTS选项是对结构的字段数进行统计，如果有内嵌的结构，则只算直接（最高级别的）内嵌的结构，且只算做１个。

,
comp2 TYPE i.

DESCRIBE FIELD: struc1 TYPE typ1 COMPONENTS comp1,
struc1-struc2 TYPE typ2 COMPONENTS comp2.
WRITE:/ typ1,comp1,/ typ2,comp2.

DESCRIBE FIELD: struc1 TYPE typ1,
struc1-struc2 TYPE typ2.
WRITE:/ typ1,/ typ2.

v 3

u 2

LENGTH ilen

当使用IN CHARACTER MODE选项时，dobj必须是flat and character-like，针对deep data types的dobj，你只能使用IN BYTE MODE，并且此情况下返回的长度为引用所占长度（在SAP系统中每个reference的长度固定为8 bytes）

对于固定长度类型的dobj，是在创建这个变量时就已决定。如果字符串类型，则不会计算尾部空格，此时可以使用预置函数strlen来测定

,
      blen TYPE i,
      clen TYPE i,
      bytes TYPE i.

DESCRIBE FIELD text LENGTH blen IN BYTE MODE.
DESCRIBE FIELD text LENGTH clen IN CHARACTER MODE.
bytes = blen / clen.
WRITE:/ blen,clen,bytes.

2 1 2

DECIMALS dec

dobj的小数位

,
i TYPE i.
DESCRIBE FIELD p DECIMALS i.
WRITE:/ i.

OUTPUT-LENGTH olen

测试dobj屏幕输出宽度，对于那些固定长度数据类型，输出宽度都是已经预置好的，对于strings，则为0

Numeric Data Types

Data Type	Output length
b	3
s	5
i	11
p	2 x length of dobj (+ 1, if there is a decimal separator)
decfloat16	24
decfloat34	46
f	24

注：上面表中的s类型显示宽度只有5位，不中以显示符号；i显示宽度为11,可以显示符号

Character-like data types

Data Type	Output Length
c	Length of dobj, maximum 255
string text field literals	根据屏幕列表设置的最大宽度来决定。如果字符不满List设置的宽度时，left-justified输出时会在右边补空格，right-justified输出时会在左边补空格，centered outputs输出时两端补空格
n	Length of dobj, maximum 255
d	8
t	6

Byte-Like Data Types

Data Type	Output Length
x	2 x length of dobj, maximum 255
xstring	2 x number of bytes contained

DATA: date1 TYPE d,
      date2 TYPE sy-datum,
      olen1 TYPE i,
      olen2 TYPE i.

DESCRIBE FIELD date1 OUTPUT-LENGTH olen1.
DESCRIBE FIELD date2 OUTPUT-LENGTH olen2.

WRITE: / date1,date2,/ olen1,olen2.

00000000 00.00.0000

8 10

HELP-ID hlp

DATA: carrid TYPE spfli-carrid,
      hlp    TYPE string,
      struc TYPE dfies-tabname,
      comp   TYPE dfies-fieldname.
DESCRIBE FIELD carrid HELP-ID hlp.
SPLIT hlp AT '-' INTO struc comp.
WRITE:/ hlp, / struc,/ comp.
CALL FUNCTION 'F4IF_FIELD_VALUE_REQUEST'
EXPORTING
    tabname   = struc
    fieldname = comp.

EDIT MASK mask

If a conversion routine is assigned to the data object dobj by referring to a domain in ABAP Dictionary, two equals signs "==" precede the name of the conversion routine and the result is assigned to the data object mask.

.
WRITE / seconds USING EDIT MASK msk.

==SDURA

5:33

DESCRIBE TABLE

DESCRIBE TABLE itab [KIND knd] [LINES lin] [OCCURS n].

不同的选项使你能够判断表类型、行数、初始化大小。另外，系统字段sy-tfill 和 sy-tleng 保存着表行数量和以字节计的表行长度。注：为了更详细的关于内表的信息，应用RTTS的方法代替语句describe table。没有指定一个附加项，语句describe table 只设置系统字段sy-tfill 和sy-tleng的值。

a) KIND knd

标识为T 时代表标准表，为S时代表排序表，为H时代表哈希表。这些值在类型组SYDES中已被定义成常量sydes_kind-standed ，sydes_kind-sorted，sydes_kind-hashed。

b) LINES lin 内表表行数量

注：在版本6.10中，内表表行的当前数量也可以用内建函数lines来判断

c) OCCURS n

在内表用选项initial size 或者老式的选项ocurs创建期间决定内表所需要的初始化内存大小

.
DESCRIBE TABLE itab KIND tabkind.
IF tabkind = sydes_kind-standard OR
     tabkind = sydes_kind-hashed.
    SORT itab DESCENDING.
ELSEIF tabkind = sydes_kind-sorted.
    MESSAGE '...' TYPE 'E'.
ELSE.
    MESSAGE '...' TYPE 'E'.
ENDIF.
ENDFORM.

DESCRIBE DISTANCE

DESCRIBE DISTANCE BETWEEN dobj1 AND dobj2 INTO dst
IN {BYTE|CHARACTER} MODE.

dobj1 and dobj2两个变量地址起始位置的距离

,
        comp3 TYPE c LENGTH 4 VALUE 'Hey',
        comp4 TYPE c LENGTH 4 VALUE 'you!',
        comp5 TYPE x,
      END OF struc.
DATA: off TYPE i,
      len TYPE i,
      len2 TYPE i.

FIELD-SYMBOLS: <hex> TYPE x,
<result> TYPE c.

DESCRIBE DISTANCE BETWEEN:
         struc       AND struc-comp3 INTO off IN BYTE MODE,
         struc-comp3 AND struc-comp5 INTO len IN BYTE MODE,
         struc       AND struc-comp1 INTO len2 IN BYTE MODE.

ASSIGN: struc TO <hex> CASTING,
<hex>+off(len) TO <result> CASTING.

WRITE: / 'Offset off is', off,
       / 'Length len is', len,
       / '<result> points to', <result>,
       / len2.

Offset off is 6

Length len is 16

<result> points toHey you!