topic Re: Why three levels?? in Application Development and Automation Discussions

Why three levels??

Former Member — Mon, 10 Dec 2007 11:01:29 GMT

Hi experts,

Why any fields in the data dictionary has three levels of hierarchy or grouping? Why do we have data elements,domain and data types?Why datatypes alone is not sufficient for any field?

I will reward points for clear explanations.

TIA

Abhishek

Re: Why three levels??

Former Member — Mon, 10 Dec 2007 11:42:53 GMT

A field in SAP DDIC is defined using domain and data

elements.

Domain describes the data type and length of the field,

ie it gives the technical details of the field.

And, Data element describes what the data element means

in business context, ie the semantic information

regarding the field. (You get the same through the F1

documentation.)

DDIC is responsible for enforcing the data integrity,

and managing data without redundancy. Now data

redundancy is reduced by linking similar information to

the same data definition. For example, an employee

table will contain Name, so will be the case in a

Customer table. Now both of the information are of

similar technical qualities however they are of

different semantic details. In this case to avoid

redundancy we can use the same domain for name fields

in both the fields and use different data elements for

the semantic details.

Besides, this helps in easy access of development

objects. Having similar objects can help us find

different objects of similar kind.

Hope this was helpful.

Regards,

Rajesh. K. Soman

For further reading you can refer the link below.

http://en.wikipedia.org/wiki/ABAP#The_ABAP_dictionary

Re: Why three levels??

Former Member — Mon, 10 Dec 2007 11:44:01 GMT

Hi Abhishek,

Data Type and Length are the characterstics that are common in betwween data-element and data-domain. There are other things which signify the importance of both in the dictionary.

Please see the creation screen for both the items and you will get the desired information.

Regds,

Gaurav

Re: Why three levels??

Former Member — Mon, 10 Dec 2007 11:53:49 GMT

Hi Abhishek,

Usage of Data elements & domains supports reusability.

You must be knowing that data element defines sematic characters & domain defines technical characters.

say for example,

You want to create tables customer_detials, Vendor_details & employee_details.

All the 3 tables contains the name of the customer or vendor or employee.

You create a domain of CHAR(20) which can be used in dataelement of first name, second name, surname. These data elements can be used in the tables.

Thus later if you decide to increase/decrease the size assigned to any of the fields, its enough to change in domain else you need to change in first name, second name & surname of all tables which is cumbersome.

Thats why 3 levels which eases the maintenance.

Regards,

Naga Sai Swapna

Re: Why three levels??

Former Member — Mon, 10 Dec 2007 12:25:36 GMT

Why any fields in the data dictionary has three levels of hierarchy or grouping?

Answer:

A Unique or one way of representing Data Types are Domain.

Data types can be of two types one of which is elementary type which again has two options Domain and Built in Type(Mostly customized) . This explains Domain

Data types --> 1)elementary

i)Domain ii)Built in

-->2) Reference Type which is again divided in to i))Name of Ref type and ii))Reference to Predefined Type

Data elements ---> Data Types

|____Domain

Why datatypes alone is not sufficient for any field?

Answer:

Your Data element is your SAP Table Fields which you use in real scenarios like for example an Employee table has emp no,empname

empno - data element data type can be INT (4) which can also be domain

or declare reference type instead of domain

Data types should have either Elementary type or Reference type.

CHECK SE11 for more information.

Reward Points if useful.

Thanks,

Anita