09 kaavian data dictionary

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DATA DICTIONARY

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Purpose

The ABAP Dictionary serves as the central description of data

used in R/3 system .

It Supports the creation and management of Metadata.

New or modified information is automatically provided for all the

system components.

It ensures data integrity, data consistency and data security.

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For Example You declare a variable in your program

DATA: MARA_TAB TYPE MARA.

Only structure MARA_TAB is declared in the program.

All the information about this structure, such as the field

names, data types and field lengths, are copied from table

MARA, which is defined in the ABAP Dictionary. This

information about table MARA is called from the ABAP

Dictionary when the program is generated.


Integration in the ABAP workbench


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Object Types


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Tables

Tables can be defined independently of the database in the

ABAP Dictionary.

The table definition is translated from the ABAP Dictionary to

a definition of the particular database.

When the table is activated, a physical table definition is

created in the database for the table definition stored in the

ABAP Dictionary.



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Reference Fields and Reference Tables

You must specify a reference table for fields containing

quantities (data type QUAN) or currency amounts (data type

CURR).

This reference table must contain a field with the format for thecurrency key (data type CUKY) or unit of measure (data type

UNIT). This field is called the reference field of the output

field. The reference field can also reside in the table itself.

A field is only assigned to the reference field at program

runtime.



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Components of Tables

Table fields : Define the field names and data types of the fields

contained in the table

Foreign keys : Define the relationships between the table and

other tables.

Technical settings : Controls how the table should be created in

the database.

Indexes : Speeds up data selection, secondary indexes can becreated for the table



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Include structure

In addition to listing the individual fields, you can also include the

fields of another structure in tables .

Only flat structures can be included.

Include structures can be included at any line of the field

definitions of the table.

The components of the structure now becomes the component of

the table.



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Append structures

An append structure is a structure that is assigned to exactly one

table or structure.

It is used to give enhancements to the already existing SAP tables

by adding fields at the last.

An append structure could be added only at the last of the table .



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Foreign keys

Foreign keys are used to maintain the referential Integrity between

dependant tables.

Foreign keys can also be used to link several tables in a view or a

lock object.

The dependant table is called foreign key table and the referenced

table is called the check table.



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Technical settings

The technical settings of a table define how the table will be

handled when it is created in the database .

The most important parameters are

Data class : Defines the Tablespace.

Size category : Defines the size of the extents created for the table.

The Buffering type should be specified if the buffering is switched

on.



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Buffering

Full buffering

All the records of the table are loaded into the buffer when one

record of the table is accessed.

Generic buffering

When a record of the table is accessed, all the records having this

record in the generic key fields are loaded into the buffer.

Single-record buffering

Only the records of a table that are really accessed are loaded into

the buffer.



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Indexes

Indexes are used for faster Access in the Database.

Two types of indexes:

Primary indexes

Secondary indexes

Primary indexes are created automatically from the key fields

of the table.

Secondary indexes are created by the user specifying the

fields in the table.

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Views

A view is used to project and select the fields from more than

one table as a single structure.

View does not store the data physically of its own.



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Types of Views

Database Views

Projection Views

Help Views

Maintenance Views



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Database Views

Database Views are used to project the particular fields from the

different tables using conditions.

A corresponding view is created in the database and hence the

technical setting should be maintained.

The foreign key relationship is not required for joining.

Always inner join is performed.



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Projection Views

It is used to project only the particular fields of a table.

The selection of records is not possible.

The maintenance status could be set to read and change the

records.



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Help Views

A help view is created if a view with outer join is needed as

selection method of a search help.

Foreign key relationship should exist between the tables.

It always implements an outer join.



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Maintenance View

Its used for maintaining complex database objects as a single

logical unit.

It implements outer join.

Foreign key relationship should exist between the tables.

Insertion and deletion is possible in the view.

SM30 is the transaction used for maintaining it.



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Types

Data Elements

Structure

Table types



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Data elements

Data elements describes an elementary data type.

The elementary data type could be either a domain or built in

data types.

Its used to maintain the field labels.

Its used to describe the documentation for the particular data

element. (F1 Help)



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Structure

A structure is a sequence of any other data types from the

ABAP Dictionary, that is, data elements, structures, table

types, or database tables.

When you create a structure in the ABAP Dictionary, each

component must have a name and a data type.

In an ABAP program, you can use theTYPE addition to refer

directly to a structure.



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Table type

Table types are construction blueprints for internal tables that are

stored in the ABAP Dictionary

When you create a table type in the ABAP Dictionary, you specify

the line type, access type, and key.

The line type can be any data type from the ABAP Dictionary, that

is, a data element, a structure, a table type, or the type of a

database table.

In an ABAP program, you can use the TYPE addition to refer

directly to a table type.



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Domain

A domain defines a value range for a data element.

Fields or components that refer to the same domain are also

changed when the domain is changed which ensures

consistency.

A conversion routine can be assigned to a domain. This

conversion routine converts values from display format to

internal format for the fields or components that refer to this

domain.



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Conversion routines

The following function modules are assigned to conversion routine

xxxxx:

conversion_exit_xxxxx_input

conversion_exit_xxxxx_output

conversion_exit_xxxxx_input is used to convert to the form stored

in the database.

conversion_exit_xxxxx_output is used to convert the format stored

in the database to the display format.



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Search helps

Search helps are used to provide the Input Help for the fields in the

screen.

There are two types:

- Elementary search help

- Collective Search help



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Elementary search help (example)



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Collective Search Help

A collective search help combines several elementary search helps.

You only have to specify the search helps that are to be combined

in the collective search help.



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Collective Search Help (Example)



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Lock Objects

Lock object is created and maintained by data dictionary

When two users simultaneously attempt to access the same data

record, this is synchronized by a lock mechanism

Lock Mode

E Exclusive

S Shared

X Exclusive, But not Cumulative



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Transactions

SE11 - ABAP Dictionary

SE13 - Dictionary Technical settings

SE14 - Database Utility

SE15 - Object Navigator ( Repository Information System )

SE16 - Data Browser



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Reference

The learning material contained in this PowerPoint Presentation is prepared with the

help of http://help.sap.com/ and sap press book. All rights reserved by SAP AG.

Unless otherwise specifically stated, this learning material is intended for the solepurpose of class room session, internal use and for knowledge transfer to the

Consultants.

However, for detailed information on this learning material, http://help.sap.com /sap press book may be referred.

Kaavian is not liable for any legal liability or responsibility for the accuracy,

completeness or usefulness of any information disclosed in these learning materials.

No portion of the learning materials shall be modified, reproduced or transmitted in

any form by any means, whether by electronic, photocopier or otherwise without thewritten permission of Kaavian. In no event shall Kaavian be liable for any damage

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09 kaavian data dictionary

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