Solved: LDB

Former Member · ‎2007 Jun 30

What are logical databases? What are the advantages/disadvantages of logical databases?

Regards

Priya

Former Member · ‎2007 Jun 30

Hi Priya

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.

adv:-

The programmer need not worry about the primary key for each table.Because Logical database knows how the different tables relate to each other,and can issue the SELECT command with proper where clause to retrieve the data.

i)An easy-to-use standard user interface.

ii)check functions which check that user input is complete,correct,and plausible.

iii)meaningful data selection.

iv)central authorization checks for database accesses.

v)good read access performance while retaining the hierarchical data view determined by the application logic.

disadv:-

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).

Regards

Ravi

Former Member · ‎2007 Jun 30

Hi Priya

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.

adv:-

The programmer need not worry about the primary key for each table.Because Logical database knows how the different tables relate to each other,and can issue the SELECT command with proper where clause to retrieve the data.

i)An easy-to-use standard user interface.

ii)check functions which check that user input is complete,correct,and plausible.

iii)meaningful data selection.

iv)central authorization checks for database accesses.

v)good read access performance while retaining the hierarchical data view determined by the application logic.

disadv:-

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).

Regards

Ravi

Former Member · ‎2007 Jun 30

Hi Priya,

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.

GET will fetch the table data immediately

GET LATE

In the LDB when you define the table structure in hierarchy, first it will fetch the higher node data and then all the below node tables data and comes to a second record in the top node table. for this GET Late is used.

You can create any number of primary keys in a table

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