hi,
Logical databases are special ABAP programs that retrieve data and make it available to application programs. The most common use of logical databases is still to read data from database tables by linking them to executable ABAP programs.
However, from Release 4.5A, it has also been possible to call logical databases using the function module LDB_PROCESS. This allows you to call several logical databases from any ABAP program, nested in any way. It is also possible to call a logical database more than once in a program, if it has been programmed to allow this. This is particularly useful for programs with type 1.
Logical databases contain Open SQL statements that read data from the database. You do not therefore need to use SQL in your own programs. The logical database reads the program, stores them in the program if necessary, and then passes them line by line to the application program or the function module LDB_PROCESS using an interface work area.
Logical Databases - Views of Data
A logical database provides a particular view of database tables in the R/3 System. It is always worth using logical databases if the structure of the data that you want to read corresponds to a view available through a logical database.
The data structure in a logical database is hierarchical. Many tables in the R/3 System are linked to each other using foreign key relationships. Some of these dependencies form tree-like hierarchical structures. Logical databases read data from database tables that are part of these structures.
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 THE 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
Use Tcode SE36 For creating Logical Database.
Here is a simple Program on Logical database.
NODES: spfli,sflight.
START-OF-SELECTION.
WRITE 'Test Program for GET'.
*Fetching SPFLI table
GET spfli.
WRITE: / 'Carrid:', spfli-carrid,
'Connid:', spfli-connid.
*Fetching SFLIGHT table
GET sflight.
SKIP 5.
WRITE: / 'Carrid:', sflight-carrid,
'Connid:', sflight-connid.
http://help.sap.com/saphelp_nw04/helpdata/en/60/183d78163011d2953c0000e8353423/frameset.htm
example program
http://help.sap.com/saphelp_nw04s/helpdata/en/9f/db9be035c111d1829f0000e829fbfe/frameset.htm
regards,
pavan
REWARD POINTS IF USEFUL
Bluesky
