03_abap - the data dictionary

7/30/2019 03_ABAP - The Data Dictionary

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ABAP - The Data Dictionary


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Contents

Objectives


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Contents

Exploring the Types of Tables

in ECC


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3 table types

transparent

tables

pooled tables

cluster tables


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Transparent Tables

transparent table vs. database table:

one-to-one relationship

same name

same number of fields same field names

used to hold application data:

master data: vendor master data, customermaster data

transaction data: purchasing order, sales order


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Contents

Exploring Table Components


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Table Components

Field: A table is composed of fields.

Data element: contains the field labels and onlinedocumentation (also called F1 help) for the field -business context.

Domain: A data element's definition requires a domain.The domain contains the technical characteristics of afield, such as the field length and data type.

Domains and data elements are reusable. A domaincan be used in more than one data element, and a dataelement can be used in more than one field and inmore than one table.


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Table Components


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Example


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Naming Conventions

Object Type Max Name Length Allowed FirstCharacter

Table 16 y, z

Data element 30 y, z

Domain 30 y, z

Field 30 Any character

Naming Conventions for Tables, Fields, Data Elements, and Domains created

by the Customer


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Contents

Creating a Transparent Table

and Its Components


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Ex: Create Vendor table

Field Name PK DE Name DM Name Data Type Length

mandt x mandt

lifnr x zlifnr zlifnr CHAR 10

name1 zname1 zname1 CHAR 35

regio zregio zregio CHAR 3

land1 zland1 zland1 CHAR 3

Fields and Their Characteristics for Table ZLFA1


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Approaches for Creating Tables

bottom-up: create domains data elements table Create domains: zlifnr, zname1

Create data elements: zlifnr, zname1

Create table: zlfa1

Create fields: lifnr, name1 Tcode used: SE11

top-down: create table data elements domains Change table: zlfa1

Create field regio data element zregio domain zregio Create field land1 data element zland1 domain

zland1

Tcode used: SE11


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Bottom-up: create domains


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Bottom-up: create domains

B tt t d t


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Bottom-up: create data

elements

B tt t d t


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elements


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B tt t d t


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elements


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Bottom-up: create table


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Bottom-up: create table


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Top-down


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Top-down


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Top-down


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Top-down


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Top-down


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Technical Settings

The data class determines the tablespace in which a table iscreated.

tablespaces is used to organize and maintain the database.

makes database administration easier

increases system performance

The size category:

the size of the initial extent

next extents

number of possible next extents


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Technical Settings

Buffering:

increases system performance by caching data locally on the

application server

fewer database accesses

used for tables that are seldom updated and often read.

Automatic logging feature:

causes a change document to be created each time the table is

changed

slows table updates

only used for tables containing critical data

non-critical tables, change document objects should be used.


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Contents

Special Table Fields


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currency fields:ex: 1000 U.S. dollars.

currency field: data type in the domain must be CURR (number 1000) currency key field: type CUKY ( USD)

quantity fields:numeric measurement (ex: 20 pieces)

The data type in the domain must be QUAN. ( 20) It must be linked to a field of type UNIT. ( PCs)


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Contents

Modifying Tables


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Modifying Tables

copy

delete

add more fields

delete fields

change fields


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Copying a Table

Copy table ZLFA1 to ZLFA1_COPY

Only copy the table structure


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Adding Fields

Inserting:

position a field before an existing field.

Appending:

add new fields at the end of the table, after all of

the existing fields.


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Inserting a Field


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Appending a Field


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Deleting Fields


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Contents

Working with Data


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Data browsers

search for and display rows that meet

specified criteria

add new rows

modify existing rows

delete rows


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Using tcode SE11

U i d SE16 D B


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Using tcode SE16 - Data Browser

C t t


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Contents

Structures in the Data

Dictionary

St t


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Structures

The differences between a structure and a table:

A structure doesn't have an associated database table

doesn't have a primary key.

doesn't have technical attributes.

Structures follow the same naming conventions as transparenttables, and you cannot have a table and structure of the samename.

The procedure for creating a structure is almost the same as forcreating a transparent table.

St t


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Structures

U d t di I l d


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Understanding Includes

A structure/table can contain another structure (nested)

C t t


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Contents

Revised and Active Versions

R i d d A ti V i


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Revised and Active Versions

Two versions of a DDIC object:

Revised version

when change save without activate Active version

when activate Revised version becomes active and replaces the Activeversion


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Compare Versions


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Compare Versions

Additional Versions


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Additional Versions

temporary versions:

menu path Utilities->Versions->Generate version

is kept until the table is transported into production

to view: menu path Utilities->Versions->Version Management

Retrieve Previous Version


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Retrieve Previous Version


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Summary The Data Dictionary is a tool used by ABAP/4 programs to create and

maintain tables. There are three types of tables: transparent, pooled,and cluster. Transparent tables are the most common and are used tocontain application data.

To create a table, you first need domains and data elements. Domainsprovide the technical characteristics of a field; data elements providethe field labels and F1 help. Both are reusable.

Within a table, each currency field must be linked to a currency key

field, and each quantity field must be linked to a field containing theunits of measurement.

Data browsers enable you to display and modify the data within tables.SE16 is the most general data browser.

Tables and structures are very similar. The main difference is that atable has an underlying database table and a structure doesn't.

Dictionary objects must be active before they can be used. If you makea change to a dictionary object, you must reactivate the object beforethe changes take effect.

03_abap - the data dictionary

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