ABAP INTERNAL TABLE

Attributes of Internal table:

* Line Type : Data type is normally structure.

* Key :  

                         -Standard Key (Default key)

u                         -User defined key.

* Table Type : It determines how ABAP will access individual table entries.

                      
Types :   Standard table – Indexed 

                Sorted table – Indexed

                Hashed table


Standard table : 

u

     - Have an internal linear index. 

u     - Access uses a linear search.

u     - Access either by key or index.

u     - Always non-unique.

u     - Response time for key access is proportional to number of entries in table

u     - This can filled quickly….no system checks on uniqueness of entries

Sorted table :

u     - Always saved sorted by key.

    u     - Have internal linear index.

u     -  Access either by key or index.

u     -  Table can be unique or non-unique.

u     - Response time for key access is logarithmically proportional to the no. of entries since binary search is used.

Hashed table :

u     -  No internal linear index.

u     -  Access only using key.

u     -  Response time for access is independent of no. of table entries since system accesses the table using hash algorithm.

u     -  Table key must be unique.

Populating Internal Tables:

For filling data into internal table : 

          - APPEND

          - INSERT

          - MODIFY

          - DELETE

          - MOVE

For fetching data from internal table : 

          - loop at <itab> into <wa>.     " fetch the record and holds in "wa"

            Endloop.

          -  Read.