topic Re: logical database in Application Development and Automation Discussions

logical database

Former Member — Thu, 10 May 2007 12:13:16 GMT

hi all

could you give me some basic funda of logical database.

points will be rewarded

thanks

Re: logical database

Former Member — Thu, 10 May 2007 12:15:27 GMT

Hi,

Logical databases, InfoSets, and table joins are all different techniques for consolidating data from multiple database tables. Logical databases are pre-defined paths for accessing database tables. These paths can be made available to various reports in code form. Logical databases are especially useful if the structure of the data you want to read corresponds to a hierarchical view. This can be realized using a logical database.

Please check this :-

http://help.sap.com/saphelp_47x200/helpdata/en/9f/db9b5e35c111d1829f0000e829fbfe/frameset.htm

Reward if found helpful.

Regards,

Deepu.K

Re: logical database

Former Member — Thu, 10 May 2007 12:22:01 GMT

Hi deepu

you said Logical databases are predefined paths.can't we define he those paths as per needs?

how these paths are made available to various reports?

why the logical database is used only when the data corresponds to hierarchical view?.

please answer

Thanks

Re: logical database

Former Member — Thu, 10 May 2007 12:28:06 GMT

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.

LDB offers an easy-to-use selection screens. You can modify the pre-generated selection screen to your needs. It offers check functions to check whether user input is complete, correct, and plausible. It offers reasonable data selections. It contains central authorization checks for data base accesses. Enhancements such as improved performance immediately apply to all report programs that use the logical database.

Less coding s required to retrieve data compared to normal internel tables.

Tables used LDB are in hierarchial structure.

Mainly we used LDBs in HR Abap Programming.

Where all tables are highly inter related so LDBs can optimize the performance there.

Check this Document. All abt LDB's

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.highlightedcontent?documenturi=%2flibrary%2fabap%2fabap-code-samples%2fldb+browser.doc

GO THROUGH LINKS -

[Removed by the moderator.]

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

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

[Removed by the moderator.]

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

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

Gothru the blog which provides info on LDB's:

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

Reward points if useful

Regards

Anji

Re: logical database

Former Member — Thu, 10 May 2007 12:29:54 GMT

Hello Ganesh,

The LDB's are nothing but the code is already written and the data is already extected.

NOw if u know the purpose of an LDB and if u want to get the same output as per the functionality of the LDB then u will maintain this LDB in ur program attributes.

Then u have to simply supply the attributes to it as PUT and get the output by using GET.

can't we define he those paths as per needs?

The path is already defined . U have to use it in ur scenario accordingly.

how these paths are made available to various reports?

Maintain this in ur Report attributes.

why the logical database is used only when the data corresponds to hierarchical view?.

Bcoz it's based on the NODAL Catalogue.

All nodes are built as per the data requested.

So each node's child segemnts are populated and then the values are extracted.

SO it's used in a hierarchical view.

Please reward if helpful.

Regards,

Deepu.k

That's it.

Re: logical database

Former Member — Thu, 21 Jun 2007 12:00:06 GMT

hi ganesh,

hope this might help you.

logical data base are special abap program that retrive data from data base and make it available for the application program.

just go to:

goto-> atrribute-> logical data base (there give PNP) in se 38 and save

write you report and exicute(no need to give parameters)

the parameter are supllied to the report by the ldb.

regrads

anuj.

Re: logical database

Former Member — Thu, 21 Jun 2007 12:23:57 GMT

Hi,

What is logical database?

The LDB is special type of ABAP program that combines the contents of certain related database tables and retrieve some related data and make it available to application programs.

In other words, a LDB is a method by which ABAP programs read and process the data. The sequence in which the data is supplied to the program is determined by a tree structure.

The LDB usually consists of the following components.• Structure

• Selections

• Database programs

Logical databases have a tree structure.

A logical database can contain a maximum of 300 tables

SAPDBPNP is the name of the database program for the

logical database PNP.

How are logical database used1

Logical databases when generating an ABAP programo The selection screen generated contains the selections (SELECT-OPTIONS AND PARAMETERS) of both the logical database and the program.

o The only database-specific selections displayed on the selection screen are those needed by the program for data retrieval purposes

2. Logical databases at run-time of an ABAP program

At run-time, the system processes the events in the program

and in the logical database in the following order

o Before displaying the selection screen, certain initializations

(e.g. calculating default values such as key date, etc.) are

performed for the selection screen by the logical database

and the program.

o The selection screen is displayed and the user enters data in the input fields.

o The logical database and the program check that the input is correct and complete , but also that the user has the appropriate authorizations. If an error occurs, some fields are made ready for input again, so that the user can make the necessary correction(s).

o In the event START-OF-SELECTION, the ABAP program

performs any preliminary work (for ex, importing files).

o The logical database reads the selected data and the program

processes it within the GET events according to the sequence

specified by the structure.

o In the event END-OF-SELECTION, the ABAP program performs

Thanks

Srinu