Logical Database Frequently Asked Questions FAQs
1. Preparation of the data records by the L.D.B and reading of the data records in the actual report are accomplished with the command pair Put and Get.
2. The three main elements of LDB are Structure, Selections, and Database Program.
3. In LDB what determines hierarchy of the tables?
4. In general what are the two ways in which one can retrieve data from tables?
Using Select statements, Database Program.
5. With LDB one can modify the pre-generated selection screen to their needs (T/F).
6. Logical databases are programs that read data from Database tables (Dictionary Structures).
7. The event Get
LATE process all tables that are hierarchically superior to the. (True/False) False. It processes all tables that are hierarchically inferior to the. 8. The Database Program of LDB is a collection of SUBROUTINES, which selects data and passes it to the report. 9. The layout of the Database program is determined by both Structure and Selections. 10. The order in which data is made available to the report depends on Structure of the LDB. 11. Apart from the structure and selections of the LDB the GET statements in the report determines the behavior of the database at runtime. 12. Node at the highest level in the structure is known as Root. 13. There can be more than one node at the highest level in the structure. (T/F) False. One can define only one node at the highest level in the structure on LDB. 14. All nodes in the structure of LDB need not be defined in the ABAP/4 Dictionary (T/F). False. One has to define all nodes in the Dictionary or one has to select all nodes that are defined in the Dictionary. 15. It is not possible to use ABAP/4 Dictionary Structures without an underlying database using LDB. (T/F) True. One can use additionally related tables, along with the tables defined in the structure of LDB. 16. Dynamic selections allow the user to define further selections for database access in addition to the selection criteria already defined in the LDB selections. 17. Check statement can be used along with the event GET in the report for checking the selections, which are not table-specific values. 18. In sense of Database Management System (DBMS) LOGICAL DATABASE is a database Structure. (T/F). False. 19. It is not necessary to maintain the Parent-Child relationship between the tables in Logical Database Structure. (T/F) False. One has to maintain the Parent-Child relationship. 20. Is it possible to extract data from tables without using the event ‘GET’ in the report with an appropriate LDB. (T/F). False. One can extract data from tables using Select statements in a report, though the report is having a LDB attribute. 21. What sorts of tables one can se in designing the hierarchy of a LDB? Tables, which are having Foreign Key relations. 22. A report program, which uses only SELECT statements, is called SQL Report. 23. One cannot use SELECT statements in a report program linked to a Logical Database (T/F). False. 24. Is it true that the Logical Database reads the data from the database tables using Select Statements (T/F). Yes. We are coding that in Database part of LDB.25. In a report with an LDB attribute, you do not have to define how the information should be retrieved from the database tables, but only how the data should be represented on the screen. (T/F). True. 26. One can use the event GET in a report without LDB attribute. (T/F). False. 27. The last character of the LDB name denotes Application. 28. The structure of Logical Databases reflects the Foreign Key dependencies of hierarchical tables in the SAP system. 29. It is mandatory that for each table in the LDB hierarchy there should exist one GET statement in the report. (T/F). False. It is not necessary. 30. What happens if a report does not contain a GET statement for a particular node of a Logical Database. Process will transfer to the next event. 31. In a Logical Database, one can define input fields on the selection screen with Select-Options and Parameters statements. 32. Suppose a logical database program contains the following lines: SELECT-OPTIONS CONNID FOR SPFLI-CONNID. PARAMETERS CARRID LIKE SFLIGHT-CARRID FOR TABLE SFLIGHT. What will be the output, for the above two statements? Only select-options connid for spfli-carrid will be displayed on the screen.33. Consider a report with F1S attribute, what will be the output for the following code. Whether you will get the data from spfli and sflight or not, with corresponding tables statement,
Write:/ spfli-carrid, spfli-connid, sflight-fldate, sbook-bookid.
Yes, you will get the data from spfli and sflight.34. Consider a report with F1S attribute, what will be the output of the following code. Whether you will get the data from sbook or not, with corresponding tables statement.
Write:/ spfli-carrid, spfli-connid, sflight-fldate, sbook-bookid.
You cannot extract data from sbook.35. Identify any errors in the following code and correct the same, and what will be the output. If there exists corresponding tables statement, for spfli, sflight, sbook.
Write:/ spfli-carrid, spfli-connid, sflight-fldate, sbook-bookid, sbook-class.
No syntax errors. You will get data from all the three tables.36. Does the following two statements do the same task? If so which one takes less time and which one is recommended.
Select * from spfli where spfli-carrid = ‘LH’ and spfli-connid = ‘400’.
Select * from spfli. Check: spfli-carrid = ‘LH’ and spflid-connid = ‘400’.
-Yes they will do the same task. Second Select statement takes less time and is recommended.37. If you want to improve the response time (time to access data) Logical Databases permits you to achieve this using VIEWS.
38. Is there any upper limit (max) to the possible number of nodes in a logical database structure? If so what is the limit?
Yes, there is an upper limit for defining number of nodes in a Logical Database Structure.
Maximum nodes = 1200 / length where length = max. Length of name in the structure.39. In the structure of Logical Database nodes at different levels are displayed in the same columns. (T/F) If false what types of nodes are displayed in the same columns. If true what type of nodes are not displayed in the same columns.
False. Nodes at same levels are displayed in the same columns.40. What are the advantages of Logical Databases?
It 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.41. Though all the ABAP/4 Dictionary Structures that exists in the structure of the LDB, being defined in Database Program, we are defining the Dictionary Structures in the Report. What is the reason for such declaration?
By declaring so we are providing work areas for data passing between Logical Database and Report. In addition, the logical database configures the selection screen depending on the selection of database tables.42. Is it mandatory to declare all the tables in Report by the key word tables for all the tables that exist in the structure of LDB, and are being defined in the Database part of LDB.
No, It is not mandatory to declare all tables in report.43. If one wants to access data using Logical Database, the use of events is unavoidable. (T/F). True.