topic Re: internal tables in Application Development and Automation Discussions

internal tables

Former Member — Fri, 07 Mar 2008 08:43:44 GMT

Hi,

how many types of internaltables which criteria we use them in our program.

Re: internal tables

Former Member — Fri, 07 Mar 2008 08:51:18 GMT

Hi,

Internal Tables are of following types:

STANDARD TABLE

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.

SORTED TABLE

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

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

INDEX TABLE

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

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.

Reward if helpful.

Regards.

Re: internal tables

Former Member — Fri, 07 Mar 2008 08:51:38 GMT

types of internaltables :

-->standard tables

-->sorted tables

-->hashed tables

STANDARD table

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

You should use index operations to access standard tables.

SORTED table

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.

HASHED table

Defines the table as one that is managed with an internal hash procedure

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

A table that can be accessed using an index.

Index table is only used to specify the type of generic parameters in a FORM or FUNCTION. That means that you can't create a table of type INDEX.

Standard tables and sorted tables are index tables.

Normally we use standard tables to increase the performance.

regards,

vineela.

Re: internal tables

Former Member — Fri, 07 Mar 2008 08:52:05 GMT

hi,

refer to the links.

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

What Are Different Types Of Internal Tables and Their Usage

Standard Internal Tables

Standard tables have a linear index. You can access them using either the index or the key. If you use the key, the response time is in linear relationship to the number of table entries. The key of a standard table is always non-unique, and you may not include any specification for the uniqueness in the table definition.

This table type is particularly appropriate if you want to address individual table entries using the index. This is the quickest way to access table entries. To fill a standard table, append lines using the (APPEND) statement. You should read, modify and delete lines by referring to the index (INDEX option with the relevant ABAP command). The response time for accessing a standard table is in linear relation to the number of table entries. If you need to use key access, standard tables are appropriate if you can fill and process the table in separate steps. For example, you can fill a standard table by appending records and then sort it. If you then use key access with the binary search option (BINARY), the response time is in logarithmic relation to

the number of table entries.

Sorted Internal Tables

Sorted tables are always saved correctly sorted by key. They also have a linear key, and, like standard tables, you can access them using either the table index or the key. When you use the key, the response time is in logarithmic relationship to the number of table entries, since the system uses a binary search. The key of a sorted table can be either unique, or non-unique, and you must specify either UNIQUE or NON-UNIQUE in the table definition. Standard tables and sorted tables both belong to the generic group index tables.

This table type is particularly suitable if you want the table to be sorted while you are still adding entries to it. You fill the table using the (INSERT) statement, according to the sort sequence defined in the table key. Table entries that do not fit are recognised before they are inserted. The response time for access using the key is in logarithmic relation to the number of

table entries, since the system automatically uses a binary search. Sorted tables are appropriate for partially sequential processing in a LOOP, as long as the WHERE condition contains the beginning of the table key.

Hashed Internal Tables

Hashes tables have no internal linear index. You can only access hashed tables by specifying the key. The response time is constant, regardless of the number of table entries, since the search uses a hash algorithm. The key of a hashed table must be unique, and you must specify UNIQUE in the table definition.

This table type is particularly suitable if you want mainly to use key access for table entries. You cannot access hashed tables using the index. When you use key access, the response time remains constant, regardless of the number of table entries. As with database tables, the key of a hashed table is always unique. Hashed tables are therefore a useful way of constructing and

using internal tables that are similar to database tables.

Index Tables

Index table is only used to specify the type of generic parameters in a FORM or FUNCTION. That means that you can't create a table of type INDEX.

Internal tables are not DB tables. Standard and Sorted tables in combined are basically called as Index tables and there nothing else. Here is the hierarchy

ANY TABLE

| |

Index Tables Hashed Table

| |

Standard Table Sorted Table

Internal tables

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.

Like all elements in the ABAP type concept, internal tables can exist both as data types and as data objects A data type is the abstract description of an internal table, either in a program or centrally in the ABAP Dictionary, that you use to create a concrete data object. The data type is also an attribute of an existing data object.

Internal Tables as Data Types

Internal tables and structures are the two structured data types in ABAP. The data type of an internal table is fully specified by its line type, key, and table type.

Line type

The line type of an internal table can be any data type. The data type of an internal table is normally a structure. Each component of the structure is a column in the internal table. However, the line type may also be elementary or another internal table.

Key

The key identifies table rows. There are two kinds of key for internal tables - the standard key and a user-defined key. You can specify whether the key should be UNIQUE or NON-UNIQUE. Internal tables with a unique key cannot contain duplicate entries. The uniqueness depends on the table access method.

If a table has a structured line type, its default key consists of all of its non-numerical columns that are not references or themselves internal tables. If a table has an elementary line type, the default key is the entire line. The default key of an internal table whose line type is an internal table, the default key is empty.

The user-defined key can contain any columns of the internal table that are not references or themselves internal tables. Internal tables with a user-defined key are called key tables. When you define the key, the sequence of the key fields is significant. You should remember this, for example, if you intend to sort the table according to the key.

Table type

The table type determines how ABAP will access individual table entries. Internal tables can be divided into three types:

Standard tables have an internal linear index. From a particular size upwards, the indexes of internal tables are administered as trees. In this case, the index administration overhead increases in logarithmic and not linear relation to the number of lines. The system can access records either by using the table index or the key. The response time for key access is proportional to the number of entries in the table. The key of a standard table is always non-unique. You cannot specify a unique key. This means that standard tables can always be filled very quickly, since the system does not have to check whether there are already existing entries.

Sorted tables are always saved sorted by the key. They also have an internal index. The system can access records either by using the table index or the key. The response time for key access is logarithmically proportional to the number of table entries, since the system uses a binary search. The key of a sorted table can be either unique or non-unique. When you define the table, you must specify whether the key is to be unique or not. Standard tables and sorted tables are known generically as index tables.

Hashed tables have no linear index. You can only access a hashed table using its key. The response time is independent of the number of table entries, and is constant, since the system access the table entries using a hash algorithm. The key of a hashed table must be unique. When you define the table, you must specify the key as UNIQUE.

Generic Internal Tables

Unlike other local data types in programs, you do not have to specify the data type of an internal table fully. Instead, you can specify a generic construction, that is, the key or key and line type of an internal table data type may remain unspecified. You can use generic internal tables to specify the types of field symbols and the interface parameters of procedures . You cannot use them to declare data objects.

Internal Tables as Dynamic Data Objects

Data objects that are defined either with the data type of an internal table, or directly as an internal table, are always fully defined in respect of their line type, key and access method. However, the number of lines is not fixed. Thus internal tables are dynamic data objects, since they can contain any number of lines of a particular type. The only restriction on the number of lines an internal table may contain are the limits of your system installation. The maximum memory that can be occupied by an internal table (including its internal administration) is 2 gigabytes. A more realistic figure is up to 500 megabytes. An additional restriction for hashed tables is that they may not contain more than 2 million entries. The line types of internal tables can be any ABAP data types - elementary, structured, or internal tables. The individual lines of an internal table are called table lines or table entries. Each component of a structured line is called a column in the internal table.

Choosing a Table Type

The table type (and particularly the access method) that you will use depends on how the typical internal table operations will be most frequently executed.

Standard tables

This is the most appropriate type if you are going to address the individual table entries using the index. Index access is the quickest possible access. You should fill a standard table by appending lines (ABAP APPEND statement), and read, modify and delete entries by specifying the index (INDEX option with the relevant ABAP command). The access time for a standard table increases in a linear relationship with the number of table entries. If you need key access, standard tables are particularly useful if you can fill and process the table in separate steps. For example, you could fill the table by appending entries, and then sort it. If you use the binary search option with key access, the response time is logarithmically proportional to the number of table entries.

Sorted tables

This is the most appropriate type if you need a table which is sorted as you fill it. You fill sorted tables using the INSERT statement. Entries are inserted according to the sort sequence defined through the table key. Any illegal entries are recognized as soon as you try to add them to the table. The response time for key access is logarithmically proportional to the number of table entries, since the system always uses a binary search. Sorted tables are particularly useful for partially sequential processing in a LOOP if you specify the beginning of the table key in the WHERE condition.

Hashed tables

This is the most appropriate type for any table where the main operation is key access. You cannot access a hashed table using its index. The response time for key access remains constant, regardless of the number of table entries. Like database tables, hashed tables always have a unique key. 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.

regards,

sreelakshmi

Re: internal tables

vinod_vemuru2 — Fri, 07 Mar 2008 08:57:59 GMT

Hi,

Generally we will be using 3 types of internal tables.

1. STANDARD TABLE (Prefered one)

2. SORTED TABLE

3. HASHED TABLE

Standard table uses linear search algorith when u search for a record.

In Sorted table data will be stored in sorted order. Here search will be BINARY by default.

Hashed table uses internal Hash algorithm for searching records.

There are 2 more types which we will use seldomly.

4. INDEX Table

5. ANY Table.

Out of 5, In most of the cases(95%) we will define the internal table as TYPE STANDARD TABLE OF structure.

Thanks,

Vinod.

Re: internal tables

Former Member — Fri, 07 Mar 2008 08:58:28 GMT

Hi,,

STRUCTURE:

DATA : BEGIN OF <structure_name>,

attributes..

END OF <structure_name>.

EG. CODE:

DATA : BEGIN OF STRUCTURE,

NAME(10),

COURSE(10),

AGE TYPE I,

END OF STRUCTURE.

STRUCTURE-NAME = 'KARTHIK'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

STRUCTURE-NAME = 'KARTHIK1'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

STRUCTURE-NAME = 'KARTHIK2'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

WRITE 😕 STRUCTURE-NAME, STRUCTURE-COURSE, STRUCTURE-AGE.

A structure can hold only one record. To make a structure hold multiple records, create a structure as an internal table.

INTERNAL TABLES:

SYNTAX:

DATA : BEGIN OF <internal_table_name> OCCURS <size>,

...attributes...

END OF <internal_table_name>.

Here, OCCURS statement is used to declare a structure as an internal table. The initial size of internal table ranges from 0 to 7.

0 - Allocates 8KB of memory for body area.

1 - Allocates a single-record memory.

APPEND and COLLECT statements are used to insert the values from work area into internal table body area.

APPEND - This statement will insert the record into body area even if it already exists.

COLLECT - This statement will not insert the record if it already exists, but if there is an integer value, it will add the integer numbers for the same records.

To view the contents of internal table, the following two statements are used:

LOOP - ENDLOOP - This statement is used to view the entire contents of internal table.

READ TABLE <internal_table_name> - This statement is used to view only a single record specified using index number. By default, SAP generates an index number for each record in the body area of internal table.

eg. code to create internal table without header line:

DATA : BEGIN OF STRUCTURE OCCURS 0,

NAME(10),

COURSE(10),

AGE TYPE I,

END OF STRUCTURE.

STRUCTURE-NAME = 'KARTHIK'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

APPEND STRUCTURE.

STRUCTURE-NAME = 'KARTHIK1'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

APPEND STRUCTURE.

STRUCTURE-NAME = 'KARTHIK1'.

STRUCTURE-COURSE = 'ABAP'.

STRUCTURE-AGE = '40'.

APPEND STRUCTURE.

LOOP AT STRUCTURE.

WRITE 😕 STRUCTURE-NAME, STRUCTURE-COURSE, STRUCTURE-AGE.

ENDLOOP.

READ TABLE STRUCTURE INDEX 5.

SKIP 5.

WRITE 😕 STRUCTURE-NAME COLOR 1, STRUCTURE-COURSE COLOR 1,

STRUCTURE-AGE

COLOR 1.

eg. code to create internal table with header line having KNA1 table records:

DATA BASKAR LIKE KNA1 OCCURS 0 WITH HEADER LINE.

SELECT * FROM KNA1 INTO TABLE BASKAR.

LOOP AT BASKAR.

WRITE 😕 BASKAR-KUNNR, BASKAR-NAME1, BASKAR-LAND1, BASKAR-ORT01.

ENDLOOP.

SYSTEM VARIABLES COMMONLY USED IN INTERNAL TABLES:

1. SY-TABIX - Used to create a loop index for internal table records.

2. SY-TFILL - Used to return number of records inside internal table body area. Before using this system variable, use DESCRIBE TABLE statement.

3. SY-DBCNT - Used to return number of records fetched from database table.

Eg. code using the above system variables in internal table:

DATA BASKAR LIKE KNA1 OCCURS 0 WITH HEADER LINE.

SELECT * FROM KNA1 INTO TABLE BASKAR.

WRITE 😕 SY-DBCNT COLOR 5.

DESCRIBE TABLE BASKAR.

SKIP 1.

WRITE 😕 SY-TFILL COLOR 7.

LOOP AT BASKAR.

WRITE 😕 SY-TABIX COLOR 3, BASKAR-KUNNR, BASKAR-NAME1, BASKAR-LAND1, BASKAR-ORT01.

ENDLOOP.

INTERNAL TABLE TYPES:

1. INDEXED INTERNAL TABLE

- STRUCTURED

- STANDARD

- SORTED

2. NON-INDEXED INTERNAL TABLE

- HASHED

STRUCTURED INTERNAL TABLE:

Any internal table created using BEGIN OF - END OF statements is called as structured internal table.

SYNTAX:

DATA : BEGIN OF <internal_table_name>,

..attributes..

END OF <internal_table_name>.

STANDARD INTERNAL TABLE:

SYNTAX:

DATA <internal_table_name> LIKE STANDARD TABLE OF <dbtable_name>

WITH DEFAULT/NON-UNIQUE KEY <field_name>

WITH HEADER LINE

INITIAL SIZE <size>.

Eg. code:

DATA BASKAR LIKE STANDARD TABLE OF MARA WITH NON-UNIQUE KEY MTART WITH HEADER LINE INITIAL SIZE 0.

SELECT * FROM MARA INTO TABLE BASKAR.

LOOP AT BASKAR.

WRITE 😕 BASKAR-MATNR, BASKAR-MTART, BASKAR-MBRSH, BASKAR-MEINS.

ENDLOOP.

Whenever we try to fetch a single record from the above internal table, LINEAR SEARCH OR SEQUENTIAL SEARCH technique is done here.

SORTED INTERNAL TABLE:

SYNTAX:

DATA <internal_table_name> LIKE SORTED TABLE OF <dbtable_name>

WITH DEFAULT/NON-UNIQUE KEY <field_name>

WITH HEADER LINE

INITIAL SIZE <size>.

eg. code:

DATA BASKAR LIKE SORTED TABLE OF MARA WITH NON-UNIQUE KEY MTART WITH

HEADER LINE INITIAL SIZE 0.

SELECT * FROM MARA INTO TABLE BASKAR.

LOOP AT BASKAR.

WRITE 😕 BASKAR-MATNR, BASKAR-MTART, BASKAR-MBRSH, BASKAR-MEINS.

ENDLOOP.

Internal table of this type stores the database table records in a sorted manner. The sorting technique is performed by default in ascending order while fetching the records itself.

HASHED INTERNAL TABLE:

DATA <internal_table_name> LIKE HASHED TABLE OF <dbtable_name>

WITH UNIQUE KEY <field_name>

WITH HEADER LINE

INITIAL SIZE <size>.

eg. code:

DATA BASKAR LIKE HASHED TABLE OF MARA WITH UNIQUE KEY MATNR WITH

HEADER LINE INITIAL SIZE 0.

SELECT * FROM MARA INTO TABLE BASKAR.

LOOP AT BASKAR.

WRITE 😕 BASKAR-MATNR, BASKAR-MTART, BASKAR-MBRSH, BASKAR-MEINS.

ENDLOOP.

Unlike the indexed internal tables, an index value will not be generated for internal table records. We have to specify the row id or field id to fetch a single record from the hashed internal table.

SORTING INTERNAL TABLE:

SYNTAX:

SORT <internal_table_name> BY <field_name> ASCENDING/DESCENDING.

EG. code:

DATA BASKAR LIKE SORTED TABLE OF MARA WITH NON-UNIQUE KEY MATNR WITH HEADER LINE INITIAL SIZE 0.

SELECT * FROM MARA INTO TABLE BASKAR.

*SORT BASKAR BY MATNR MBRSH MTART DESCENDING.

LOOP AT BASKAR.

WRITE 😕 BASKAR-MATNR, BASKAR-MBRSH, BASKAR-MTART, BASKAR-MEINS.

ENDLOOP.

We cannot apply sorting technique to the sorted internal table type. The default sorting technique is ASCENDING.

Regards,

Arunsri