Advise me on logical databases

Question

hi experts,
              I am working with BSEG table now .It is time consuming for me .i have followed all the instructions for using a cluster table but still it is taking time for execution.
              how can i apply logical database concepts here.
send some example codes for using LDB.
Regards,
Manikandan

Answer 1

Hi,
To read data from a database tables we use logical database. A logical database provides read-only access to a group of related tables to an ABAP/4 program.
Advantages: i)check functions which check that user input is complete, correct,and plausible. ii)Meaningful data selection. iii)central authorization checks for database accesses. iv)good read access performance while retaining the hierarchical data view determined by the application logic.
dis advantages: i)If you donot specify a logical database in the program attributes,the GET events never occur. ii)There is no ENDGET command,so the code block associated with an event ends with the next event statement (such as another GET or an END-OF-SELECTION).
If you need to find the logical database for a table name, you can used SE36 - Logical Database Bulider.
Steps :-
Go to transaction SE36
Click Extras -> Table usage
Supply the Table name and hit enter.
A Display Logical Database will be shown on a pop-up windows.
http://help.sap.com/saphelp_46c/helpdata/EN/9f/db9b5e35c111d1829f0000e829fbfe/content.htm
http://www.thespot4sap.com/Articles/SAP_ABAP_Queries_FunctionalAreas_LogicalDB.asp
Main Functions of the logical database
Standard Selection screen
Data Retrieval
Authorization check
To use logical database PNP in your program, specify in your program attributes.
Standard Selection Screen
Date selection
Date selection delimits the time period for which data is evaluated. GET PERNR retrieves all records of the relevant infotypes from the database. When you enter a date selection period, the PROVIDE loop retrieves the infotype records whose validity period overlaps with at least one day of this period.
Person selection
Person selection is the 'true' selection of choosing a group of employees for whom the report is to run.
Sorting Data
· The standard sort sequence lists personnel numbers in ascending order.
· SORT function allows you to sort the report data otherwise. All the sorting fields are from infotype 0001.
Report Class
· You can suppress input fields which are not used on the selection screen by assigning a report class to your program.
· If SAP standard delivered report classes do not satisfy your requirements, you can create your own report class through the IMG.
Data Retrieval from LDB
1. Create data structures for infotypes.
INFOTYPES: 0001, "ORG ASSIGNMENT
0002, "PERSONAL DATA
0008. "BASIC PAY
2. Fill data structures with the infotype records.
Start-of-selection.
GET PERNR.
End-0f-selection.
Read Master Data
Infotype structures (after GET PERNR) are internal tables loaded with data.
The infotype records (selected within the period) are processed sequentially by the PROVIDE - ENDPROVIDE loop.
GET PERNR.
PROVIDE * FROM Pnnnn BETWEEN PN/BEGDA AND PN/ENDDA
If Pnnnn-XXXX = ' '. write:/ Pnnnn-XXXX. endif.
ENDPROVIDE.
Period-Related Data
All infotype records are time stamped.
IT0006 (Address infotype)
01/01/1990 12/31/9999 present
Which record to be read depends on the date selection period specified on the
selection screen. PN/BEGDA PN/ENDDA.
Current Data
IT0006 Address - 01/01/1990 12/31/9999 present
RP-PROVIDE-FROM-LAST retrieves the record which is valid in the data selection period.
For example, pn/begda = '19990931' pn/endda = '99991231'
IT0006 subtype 1 is resident address
RP-PROVIDE-FROM-LAST P0006 1 PN/BEGDA PN/ENDDA.
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 -
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
/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
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
Sample code
TABLES: SPFLI,
SFLIGHT,
SBOOK,
SCARR.
START-OF-SELECTION.
GET SPFLI.
WRITE:/ ’SPFLI: ’, SPFLI-CARRID, SPFLI-CONNID,
SPFLI-AIRPFROM, SPFLI-AIRPTO.
GET SFLIGHT.
WRITE:/ ’ SFLIGHT: ’, SFLIGHT-CARRID, SFLIGHT-CONNID, SFLIGHT-FLDATE.
GET SBOOK.
WRITE:/ ’ SBOOK: ’, SBOOK-CARRID, SBOOK-CONNID,
SBOOK-FLDATE, SBOOK-BOOKID.
GET SFLIGHT LATE.
WRITE:/ ’ GET SFLIGHT LATE: ’, SFLIGHT-FLDATE.
<REMOVED BY MODERATOR>
Cheers,
Chandra Sekhar.
Edited by: Alvaro Tejada Galindo on Feb 22, 2008 6:04 PM