topic Re: logical database in Application Development and Automation Discussions

logical database

Former Member — Thu, 22 Mar 2007 05:27:38 GMT

what is logical database, how it works,what is the importantance of it

Re: logical database

Former Member — Thu, 22 Mar 2007 05:32:49 GMT

Hi,

A logical database is a special ABAP/4 program which combines the contents of certain database tables. You can link a logical database to an ABAP/4 report program as an attribute. The logical database then supplies the report program with a set of hierarchically structured table lines which can be taken from different database tables.

Advantages of Logical database -

1) No need of programming for retrieval , meaning for data selection

2) Easy to use standard user interface, have check completeness of user input.

Disadvantages

1) Fast in case of lesser no. of tables But if the table is in the lowest level of hierarchy, all upper level tables should be read so performance is slower.

GO THROUGH LINKS -

http://www.sap-basis-abap.com/saptab.htm

http://help.sap.com/saphelp_nw04/helpdata/en/9f/db9bfa35c111d1829f0000e829fbfe/content.htm

http://help.sap.com/saphelp_nw04/helpdata/en/9f/db9b5e35c111d1829f0000e829fbfe/frameset.htm

http://help.sap.com/saphelp_nw04/helpdata/en/c6/8a15381b80436ce10000009b38f8cf/frameset.htm

Siddhi

Reward points if helpful

Re: logical database

Former Member — Thu, 22 Mar 2007 05:33:09 GMT

Hi Praveen,

Check these links.

/people/srivijaya.gutala/blog/2007/03/05/why-not-logical-databases

www.sapbrain.com/FAQs/TECHNICAL/SAP_ABAP_Logical_Database_FAQ.html

www.sap-img.com/abap/abap-interview-question.htm

www.sap-img.com/abap/quick-note-on-design-of-secondary-database-indexes-and-logical-databases.htm

Hope this resolves your query.

Reward all the helpful answers.

Regards

Re: logical database

Former Member — Thu, 22 Mar 2007 05:33:12 GMT

Hi Praveen. ..

Welcome to SDN ************************

http://help.sap.com/saphelp_nw04/helpdata/en/9f/db9b5e35c111d1829f0000e829fbfe/content.htm

http://help.sap.com/saphelp_nw2004s/helpdata/en/9f/db9bb935c111d1829f0000e829fbfe/content.htm

Regards

Sudheer

Re: logical database

Former Member — Thu, 22 Mar 2007 05:41:19 GMT

Hi Sonti,

Logical databases are special ABAP programs that read data from database tables. They are used by executable (type 1) programs. At runtime, you can regard the logical database and the executable program (reports) as a single ABAP program, whose processing blocks are called by the runtime environment in a particular, pre-defined sequence.

Structure

The structure of a logical database determines the database tables which it can access. It adopts the hierarchy of the database tables defined by their foreign key relationships. This also controls the sequence in which the tables are accessed.

Tasks of Logical Databases

As well as allowing you to read data from the database, logical databases also allow you to program other tasks centrally, making your application programs less complicated. They can be used for the following tasks:

• Reading the same data for several programs.

The individual programs do not then need to know the exact structure of the relevant database tables (and especially not their foreign key relationships). Instead, they can rely on the logical database to read the database entries in the right order during the GET event.

• Defining the same user interface for several programs.

Logical databases have a built-in selection screen. Therefore, all of the programs that use the logical database have the same user interface.

• Central authorization checks

Authorization checks for central and sensitive data can be programmed centrally in the database to prevent them from being bypassed by simple application programs.

• Improving performance

If you want to improve response times, logical databases permit you to take a number of measures to achieve this (for example, using joins instead of nested SELECT statements). These become immediately effective in all of the application programs concerned and save you from having to modify their source code.

Selection Part

The selection part of the logical database defines input fields for selecting data. The runtime environment displays these on the selection screen when you run an executable program linked to the logical database. The corresponding fields are also available in the ABAP program, allowing you, for example, to change their values to insert default values on the selection screen.

Database Program

The database program of a logical database is a container for special subroutines, in which the data is read from the database tables. These subrotuines are called by the reporting processor in the runtime environment in a predefined sequence.

Regards

Avi..........

Re: logical database

Former Member — Sat, 24 Mar 2007 05:53:17 GMT

hi friends i hve a problem wiht include structure table name

this i declare in internal table like kna1 with all field of table with ,in write statement i have like

begin of itab occurs 0.

include structure kna1.

end of itab.

write: itab-kan1.

but iam not getting out put.

i tryied in some other ways also.