ABAP：从现有数据库表创建内部表的语法

Question

I'm new to ABAP. Started learning about internal tables. I was reading on the ways to create internal tables.

I came across the following syntax to create an internal table from an existing database table:

data: it_mara type table of mara.

I'm confused since mara is a table and if both lhs and rhs are of the same type then shouldn't it be just:

data: it_mara type mara.

What is the need to convert mara into a table when it is already a table?

Answer 1

Historical reasons (always a good guess...).

The original and nowadays obsolete way to declare a table (with a header line was DATA it_mara TYPE mara OCCURS 10 . Without OCCURS , you didn't declare a table, so it became a structure. My guess would be that in order to maintain backwards compatibility, that wasn't changed when TYPE TABLE OF was introduced.

Answer 2

MARA is a transparent table which means that it functions at the same time as the structure type MARA . This is the way SAP works. :)

Answer 3

SAP DDIC table (transparent table, pooled table, cluster table) function as a structure .

Internal table is a list of structure (= DDIC table ) values.

In your example of SAP DDIC table MARA (General Material Data), we can define it as an internal table like

data: it_mara type STANDARD table of mara.

which creates an STANDARD internal table

data: it_mara type SORTED table of mara.

which creates an SORTED internal table