topic internal tables in Application Development and Automation Discussions

internal tables

Former Member — Wed, 25 Jul 2007 11:51:26 GMT

when we are going to use the internal tables..

whts the use of internal tables

Re: internal tables

Former Member — Wed, 25 Jul 2007 11:55:48 GMT

Hie ,

Internal tables provide a means of taking data from a fixed structure and storing it in working memory in ABAP. The data is stored line by line in memory, and each line has the same structure. In ABAP, internal tables fulfill the function of arrays. Since they are dynamic data objects, they save the programmer the task of dynamic memory management in his or her programs. You should use internal tables whenever you want to process a dataset with a fixed structure within a program. A particularly important use for internal tables is for storing and formatting data from a database table within a program. They are also a good way of including very complicated data structures in an ABAP program.

Regards,

Bijal

Re: internal tables

Former Member — Wed, 25 Jul 2007 11:56:02 GMT

Hi,

Internal tables are a very important concept of ABAP.

They are use to store the data of database tables temporarily.

This is done to ensure that the Database is not accessed continuously.

You can do any processing on the data in the internal tables and finally save the processed data from the internal table to the database table.

ABAP doesn't support arrays.

Internal table is like multi dimensional arrays where you can store data in

rows and columns.

It contains header line.

Header line is nothing but a work area of the table.

Either you can have header line in the internal table or you can declare a work area separately.

HEADER & BODY: Every table(be it internal or transparent)contains two sections: Header and Body.

Header is a workarea of the table which acts as an interface for the table. Header can have only one record at a time

Body is the entire table containing the data or records. Body is a collection of records.

Structure of header and body are same for a particular table.

Example,

internal table.

data: begin of itab occurs 0,

matnr like mara-matnr,

maktx like makt-maktx,

end of itab.

Thanks,

Reward If Helpful

Re: internal tables

Former Member — Wed, 25 Jul 2007 11:57:38 GMT

check this:

http://help.sap.com/saphelp_nw04/helpdata/en/fc/eb35de358411d1829f0000e829fbfe/content.htm

anju

Re: internal tables

Former Member — Wed, 25 Jul 2007 12:06:03 GMT

hi,

Chk this.

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

<u>Read this notes</u>

Internal Tables

Internal tables are considered to be the true work horse of ABAP. They can have a big impact on processing and performance when programmed incorrectly. Use the quick checklist below to help guide you when coding internal table(itab) processing.

Internal Table Quick Checklist

Loop at itab must always use a work area or assign to a field symbol

Use parallel cursor technique for nested loops.

Use the TRANSPORTING clause with READ and MODIFY wherever possible to tranport only the fields necessary

Use TRANSPORTING No FIELDS clause when checking only for existence of a record

Read by INDEX is the fastest access option for a single READ. Use standard table if you are

accessing mainly by index. Consider this where possible but use caution as it does not apply to all programming situations.

Specify full key on a table read whenever possible. Use ‘WITH TABLE KEY’ clause when full key is specified

Internal Tables should be passed to FORMS with the "USING" clause. The "TABLES" clause is considered obsolete.

Internal tables should be passed to FORMS by Reference for performance reasons

i.e. do not use USING Value(..)

Do not use Occurs 0 or With Header Line unless it is a SAP function that requires it.

Hashed tables are a good performance approach over standard tables whenever random record accesses are required for a large internal table using the fully qualified key.

When sorting internal tables, always use "SORT BY Key1...n", never just "SORT" on it's own

Standard Tables require a Sort by, Delete adjacent Duplicates, and READ itab with KEY...Binary Search

Keep "SORT itab BY" statement as close as possible to the READ itab with KEY...Binary Search.

Delete Adjacent Duplicates should always be explicit by using the COMPARING clause, even if there is only one field in the itab

Standard Tables should be sorted by sorting keys to take advantage of Binary Search. However, if you sort by one key and Read with a different set, you could miss data

Regards

Reshma

Re: internal tables

Former Member — Wed, 25 Jul 2007 12:12:37 GMT

Hi,

HASHED TABLE:

U cannot use index operation in HASHED table.

Use INSERT <WA> INTO TABLE <HAS_ITAB>.

1. Hashed tables are useful if you want to construct and use an internal table which resembles a database table or for processing large amounts of data.

2. You will not be able to use the APPEND statement. Instead you can use the INSERT statement.

INSERT <wa> INTO <itab>.

3. Index operations cannot be used for hashed tables. For index tables(Standard and sorted), index operations are faster than key operations. Hashed tables are useful for reading a single data record via the table key, since the resulting access time is independent of the number of table entries. The location of the data record to be read is determined using the hash function.

4. INSERT for a standard table or hashed table using the key has the same effect as an APPEND statement.

5. /people/harry.dietz/blog/2005/10/28/performance-improvement-hints-3-internal-table--fill-and-read on internal tables(sorted,std,hashed)

STANDARD TABLE

Effect

Defines the table as a standard table. Key access to a standard table uses a linear search. This means that the timne required for a search is in linear relation to the number of table entries.

You should use index operations to access standard tables.

For the sake of compatibility, you can use TABLE as a synonym of STANDARD TABLE.

SORTED TABLE

Effect

Defines the table as one that is always saved correctly sorted. Key access to a sorted table uses a binary key. If the key is not unique, the system takes the entry with the lowest index. The runtime required for key access is logarithmically related to the number of table entries.

You can also access sorted tables by index operations. When you insert using an index, the system checks to ensure that the sort sequence has been correctly maintained. For this reason, it takes longer than inserting entries in a standard table. As a rule, you should only access sorted tables using their key.

HASHED TABLE

Effect

Defines the table as one that is managed with an internal hash procedure. You can imagine a hashed table as a set, whose elements you can address using their unique key. Unlike standard and sorted tables, you cannot access hash tables using an index. All entries in the table must have a unique key. Access time using the key is constant, regardless of the number of table entries.

You can only access a hashed table using the generic key operations or other generic operations ( SORT, LOOP, and so on). Explicit or implicit index operations (such as LOOP ... FROM oe INSERT itab within a LOOP) are not allowed.

INDEX TABLE

Effect

Standard and sorted tables belong to the generic class index tables. An index table is one that you can access using an index. You can currently only use the table type INDEX TABLE to specify the type of generic parameters in a FORM or a FUNCTION. Hashed tables are not index tables, and cannot therefore be passed to parameters defined as INDEX TABLE.

ANY TABLE

Effect

Like INDEX TABLE, you use ANY TABLE to specify the type of any generic table parameter. The set of permitted operations for a table with type ANY TABLE consists of the intersection of all permitted operations for STANDARD, SORTED and HASHED TABLEs, and so is identical to the set of operations permitted for hashed tables.

Note in particular that you cannot use index access for tables with this type.

<b>Reward if Helpful.</b>

Regards,

Karthick.

Re: internal tables

Former Member — Wed, 25 Jul 2007 12:14:00 GMT

hi,

internal tables are mainly used to maintain fixed client specified fields in the output.it improves the performance of coding. we will be populating the data into user defined internal table.therefore the master table remains unaffected.it uses memory during runtime.

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