ABAP session – 3_1-Internal Tables

7/30/2019 ABAP session – 3_1-Internal Tables

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•An Internal Table is a DATA OBJECT, in which you can keep several identically

structured data records at runtime

•The number of data records is restricted only by the capacity of the specific system

installation•The ABAP runtime system dynamically manages the size of the internal table

•The individual data sets in an internal table are known as table rows or table entries

•The individual components in a row are referred as columns or fields



Line Type- defines the structure of the row of the itab

Key – key fields of an itab including their order (depending on the access type, the

key can be defined as UNIQUE or NON_UNIQUE)

Table Kind – there are 3 different types of tables:

1. Standard Table – Use this kind of internal table if table access is mostly by

index

2. Sorted Table – Data records are automatically sorted in ascending order of

the keys. Use this kind of table if you mostly access the itab by KEY or

would like the table to be automatically sorted by the KEY

3. Hashed Table – Only KEY ACCESS is possible. Use this itab only if the

itab is very large and want to access it by KEY Only



With this you can implement tables of any structure without having to refer to an

existing dictionary structure



Remember to declare the work area and use that work area to process the single

records of the internal table

The work area has to be defined with the same type as the line type of the internal

table



CLEAR: The memory space required for the table is released, except for the initial memory

requirement.

If you are using internal tables with header lines, remember that the

header line and the body of the table have the same name.

If you want to address the body of the table itself, not the header line, during initialization using CLEAR , you must place two square brackets ([]) after the table

name.

REFRESH: This always applies to the body of the table.

With REFRESH, too, the initial memory requirement fort he table

remains reserved.

To release this memory space, use the following statement

FREE: You can use FREE to directly initialize an internal table and to release its entire

memory space, including the initial memory requirement, without first using the

REFRESH or CLEAR statements.

Like REFRESH, FREEaccesses the table body, not the table work

area.

After a FREEstatement, the internal table still exists. It still

occupies the amount of memory required for its header (currently 256 bytes).

When you refill the table, the system has to allocate new memory

space to the lines.

ABAP session – 3_1-Internal Tables

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