topic Re: Internal table in Application Development and Automation Discussions

Internal table

Former Member — Wed, 27 Dec 2006 05:31:53 GMT

Hi frnds,

what is the difference between bothe the types of declararion i mean to say technical point of view.

1) DATA : BEGIN OF ITAB 0CCURS 0,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF ITAB.

TYPES : BEGIN OF T_TAB,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF T_TAB.

data it_tab type table of t_tab.

Thnking u all.

regards,

satish

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:35:10 GMT

1) it_tab will not have a Header line where as itab will have one.

Re: Internal table

Sandeep_Panghal — Wed, 27 Dec 2006 05:35:27 GMT

Hi,

OCCURS 0 declares an internal table with work area whereas the second declration dont have an header .

We should always use the second type declaration ans declare an explicit work area like data : wa type it_tab.

Hope this helps.

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:35:57 GMT

Hi,

In the first case, your internal table has a header line & the second doesn't have it.

Re: Internal table

anversha_s — Wed, 27 Dec 2006 05:36:34 GMT

hi,

chk this u will get the idea.


*&---------------------------------------------------------------------*
*& Report  ZTYPES                                                      *
*&                                                                     *
*&---------------------------------------------------------------------*
REPORT  ZTYPES                                                  .

* Table declaration (old method)
DATA: BEGIN OF tab_ekpo OCCURS 0,             "itab with header line
  ebeln TYPE ekpo-ebeln,
  ebelp TYPE ekpo-ebelp,
 END OF tab_ekpo.

*Table declaration (new method)     "USE THIS WAY!!!
TYPES: BEGIN OF t_ekpo,
  ebeln TYPE ekpo-ebeln,
  ebelp TYPE ekpo-ebelp,
 END OF t_ekpo.
DATA: it_ekpo TYPE STANDARD TABLE OF t_ekpo INITIAL SIZE 0,      "itab
      wa_ekpo TYPE t_ekpo.                    "work area (header line)

* Build internal table and work area from existing internal table
DATA: it_datatab LIKE tab_ekpo OCCURS 0,      "old method
      wa_datatab LIKE LINE OF tab_ekpo.

* Build internal table and work area from existing internal table,
* adding additional fields
TYPES: BEGIN OF t_repdata.
        INCLUDE STRUCTURE tab_ekpo.  "could include EKKO table itself!!
TYPES: bukrs  TYPE ekpo-werks,
       bstyp  TYPE ekpo-bukrs.
TYPES: END OF t_repdata.
DATA: it_repdata TYPE STANDARD TABLE OF t_repdata INITIAL SIZE 0,   "itab
      wa_repdata TYPE t_repdata.                 "work area (header line)

http://help.sap.com/saphelp_nw2004s/helpdata/en/fc/eb3660358411d1829f0000e829fbfe/frameset.htm

Regards

Anver

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:38:44 GMT

Hi,

First type of decleration hold WA & body of table

Second decleration hold only body of table.

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:41:25 GMT

Hi All,

Thnk u for ur replies.

suppose i m declaring the second declaration as

data it_tab type table of t_tab with header line.

Then wht is the difference now.

regards,

satish

Re: Internal table

amit_khare — Wed, 27 Dec 2006 05:44:10 GMT

Hi,

DATA: BEGIN OF <itab> OCCURS <n>,

...

<fi> ...

...

END OF <itab>.

This statement declared an internal table <itab> with the line type defined following the OCCURS addition. Furthermore, all internal tables had header lines.

The number <n> in the OCCURS addition had the same meaning as in the INITIAL SIZE addition from Release 4.0. Entering ‘0’ had the same effect as omitting the INITIAL SIZE addition. In this case, the initial size of the table is determined by the system.

The above statement is still possible in Release 4.0, and has roughly the same function as the following statements:

TYPES: BEGIN OF <itab>,

...

<fi> ...,

...

END OF <itab>.

DATA <itab> TYPE STANDARD TABLE OF <itab>

WITH NON-UNIQUE DEFAULT KEY

INITIAL SIZE <n>

WITH HEADER LINE.

In the original statement, no independent data type <itab> is created. Instead, the line type only exists as an attribute of the data object <itab>.

Since Release 3.0, it has been possible to create table types using

TYPES <t> TYPE|LIKE <linetype> OCCURS <n>.

and table objects using

DATA <itab> TYPE|LIKE <linetype> OCCURS <n> [WITH HEADER LINE].

The effect of the OCCURS addition is to construct a standard table with the data type <linetype>. The line type can be any data type. The number <n> in the OCCURS addition has the same meaning as before Release 3.0. Before Release 4.0, the key of an internal table was always the default key, that is, all non-numeric fields that were not themselves internal tables.

The above statements are still possible in Release 4.0, and have the same function as the following statements:

TYPES|DATA <itab> TYPE|LIKE STANDARD TABLE OF <linetype>

WITH NON-UNIQUE DEFAULT KEY

INITIAL SIZE <n>

[WITH HEADER LINE].

They can also be replaced by the following statements:

When you create a standard table, you can use the following forms of the TYPES and DATA statements. The addition INITIAL SIZE is also possible in all of the statements. The addition WITH HEADER LINE is possible in the DATA statement.

Generic Standard Table Type:

TYPES <itab> TYPE|LIKE [STANDARD] TABLE OF <linetype>.

The table key is not defined.

Fully-Specified Standard Table Type:

TYPES <itab> TYPE|LIKE [STANDARD] TABLE OF <linetype>

WITH [NON-UNIQUE] <key>.

The key of a fully-specified standard table is always non-unique.

Short Forms of the DATA Statement :

DATA <itab> TYPE|LIKE [STANDARD] TABLE OF <linetype>.

DATA <itab> TYPE|LIKE [STANDARD] TABLE OF <linetype>

WITH DEFAULT KEY.

Both of these DATA statements are automatically completed by the system as follows:

DATA <itab> TYPE|LIKE STANDARD TABLE OF <linetype>

WITH NON-UNIQUE DEFAULT KEY.

The purpose of the shortened forms of the DATA statement is to keep the declaration of standard tables, which are compatible with internal tables from previous releases, as simple as possible. When you declare a standard table with reference to the above type, the system automatically adopts the default key as the table key.

Fully-Specified Standard Tables:

DATA <itab> TYPE|LIKE [STANDARD] TABLE OF <linetype>

WITH [NON-UNIQUE] <key>.

The key of a standard table is always non-unique.

Regards,

Amit

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:44:26 GMT

Refer this link:

http://help.sap.com/saphelp_47x200/helpdata/en/fc/eb3660358411d1829f0000e829fbfe/frameset.htm

Regards,

Ravi

Re: Internal table

anversha_s — Wed, 27 Dec 2006 05:45:16 GMT

hi,

* Build internal table and work area from existing internal table,
* adding additional fields
TYPES: BEGIN OF t_repdata.
        INCLUDE STRUCTURE tab_ekpo.  "could include EKKO table itself!!
TYPES: bukrs  TYPE ekpo-werks,
       bstyp  TYPE ekpo-bukrs.
TYPES: END OF t_repdata.

DATA: it_repdata TYPE STANDARD TABLE OF t_repdata INITIAL SIZE 0,   "itab
      wa_repdata TYPE t_repdata.                 "work area (header line)

Regards

Anver

Re: Internal table

former_member508729 — Wed, 27 Dec 2006 05:47:27 GMT

Hi ,

In this type of declaration also the table it_itab will have header line so just declaration style is different in this case.

Regards

Ashutosh

Reward points if helpful

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:48:55 GMT

hi satish,

in first example a internal table of name itab will be created directly. in second example u need to use data statement to create internal table.

DATA : BEGIN OF ITAB 0CCURS 0,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF ITAB.

this type of coding is used when structure u create is going to be used only once.

a internal table Itba will be created.

memeory area will be allocated for ITAB.

where

TYPES : BEGIN OF T_TAB,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF T_TAB.

data it_tab type table of t_tab.

this code is used to create many internal table of T_TAB structure type.

here data statement is required to create internal table.

no memory area will be created until u use data statement.

Re: Internal table

Former Member — Wed, 27 Dec 2006 05:57:43 GMT

Hi vickram,

once we give data statement then memory will be allocated then will there be any diff between the two.

regards,

satish

Re: Internal table

Former Member — Wed, 27 Dec 2006 06:03:04 GMT

hi,

if u declare with the data : begin of itab occurs 0,

this will create the internal table with the header line

and takes structure from standard.

if u declare with the types u are creating the strucutre in your

program and using that structure .

regards.

Praveen

Re: Internal table

Former Member — Wed, 27 Dec 2006 06:04:56 GMT

Hi ,

I learnt from a book that if we declare like this

DATA : BEGIN OF ITAB 0CCURS 0,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF ITAB.

it will take 8kb of memory initially . whereas

TYPES : BEGIN OF T_TAB,

MATNR LIKE MARA-MATNR,

ERNAM LIKE MARA-ERNAM,

END OF T_TAB.

Data : it_tab type table of t_tab.

in this type it will take 30 bytes (18 + 12) of memory initially .

Cheers .

Re: Internal table

Former Member — Wed, 27 Dec 2006 06:07:41 GMT

Hi,

OCCURS 0 declares an internal table with work area whereas the second declration dont have an header .

We should always use the second type declaration ans declare an explicit work area like data : wa type it_tab.

regards,

kumar

Re: Internal table

Former Member — Wed, 27 Dec 2006 06:49:20 GMT

The main difference is in "Header Line".

In the first case, there will be a header line by default.

In the second case, you are creating a type declaration, with the necessary fields and then creating an internal table of that 'type'. So this will not have any header line.

It is always advisable to use the second option i.e. first create a type declaration and then decalre an internal table of that type. Also create an expilcit Work Area of the same type declaration. This is the "Best Practice" used.

Never use header line as the performance of the code comes down. Always use explicit Work Area.

PS: If this answer is useful, plz provide Reward Points.

Re: Internal table

Former Member — Wed, 27 Dec 2006 08:20:26 GMT

The basic difference would be ....the first declaration of internal table will have a Header where as the type declaration will not have a header...

...morover if u have declared using "type"... while looping at the internal table u will have to loop into a wor areak to read and access it for computation....as for the first its not needed.