ABAP Dictionary Exercises

ECC 6.0Data Modeling & ABAP Dictionary

Study Questions and Answers

SAP Development ABAP Training

1. What represents the commercially oriented model of the real world?SAPs Enterprise Data Model (EDM) represents the commercially oriented model of the real world, while the ABAP Dictionary contains the data processing-oriented model. The EDM is the top-level overview of the entire system. At this level the exact characteristics of the relationships between entities are not important, merely knowing that the relationships exist is what matters.

2. What is an entity? How are entities represented in the ABAP Dictionary?An entity is an object that is of interest and is uniquely identifiable. It is an object about which information must be stored. Within the ABAP Dictionary, entities are stored as records in a table.

3. What is an entity type? How are entity-types represented in the ABAP Dictionary?

Entity types describe a set of entities with common attributes. Each entity type has a unique name and unique description. For example, the set of all customers would be an entity type, while each individual customer would be an entity in that type. Within the ABAP Dictionary, entity types are stored as tables.

4. What is an attribute? How are attributes represented in the ABAP Dictionary? Attributes describe an entitys (or entity types) features or characteristics. Within the ABAP Dictionary, attributes are represented as fields in a table.

5. How are business-rules represented in a data model?

Business rules are represented in a data model by relationships between entity types. The cardinality and category of those relationships help define those rules. Within the ABAP Dictionary, these relationships are implemented as foreign key relationships.

6. Name and describe the 5 entity relationship categories.

A. Hierarchical: an entity type is dependent on the existence of exactly one other entity type. In this case the primary key of the referenced entity type is inherited by the

Dependent entity type.

B. Aggregating/Associative: an entity type is dependent on the existence of multiple other entity types. This type is used to resolve many-to-many relationships. The full primary keys of the referenced entity types are inherited by the dependent entity type.

C. Referential: an entity type refers to another entity type but is not identified by the relationship. It is possible to change or eliminate the relationship, but as long as the relationship exists, it is non-optional. The primary key of the referenced entity type is passed onto the dependent entity type as a non-key field.

D. Conditional-Referential: the same as a referential relationship, but the relationship is optional.

E. Specialization: an entity type that represents a subset of the referenced entity type but also has additional attributes. In this case the referenced entity type is called the generalization, and the dependent entity type is called the specialization. Generalizations and specializations have the same primary key fields but are used to store different information in non-key fields.

7. How is the SAP Enterprise Data Model linked to the ABAP Dictionary?Via the SAP Data Modeler.

8. What within R/3 manages data definitions?The ABAP Dictionary manages data definitions so that all data is described centrally and without redundancy, thereby maintaining data integrity (all changes take immediate effect in all relevant modules and need only be entered in one location).

9. What is the DB Utility? What is its transaction code?The database utility is the interface between the data dictionary and the relational database that underlies the SAP system. It is used to create underlying tables in the database that will be used in SAP. The DB utility supports tables, table indexes, views, search helps, pools/clusters. Certain overview functions are provided: background logs, background jobs, restart logs. The processing options offered are online, background and generate program (where the program that is to execute the selected function is generated without actually executing the function). The basic functions of the DB utility are created, delete and convert, and delete, create again. There is a lock mechanism associated with the DB utility in order to ensure that an existing operation may be completed before another is triggered.

The transaction code for the DB utility is SE14.

10. Explain the concept of tables, domains and data elements.A domain is used to group together fields of similar technical characteristics. Attributes such as format (data type), length, and output characteristics are specified by the domain. A data element must be associated with a domain, and it gives a meaningful description to a field in a particular context. Tables consist of records (rows) and fields (columns). Each field in a table must be assigned to a data element (which is in turn assigned to a domain).

11. At the domain level, what within R/3 prevents the user from entering invalid data?

1. Value table

2. Explicit values

12. Within the ABAP Dictionary, what ensures data integrity between tables?

Foreign key relationships.

13. Which attributes of the answer to #12 help further define relationships between tables?Name and describe the two components of those attributes.

The semantic attributes of foreign key relationships help further define business rules and enforce data integrity. Those two attributes are cardinality (how many of one item relate to how many of another) and foreign key field type (similar to relationship categories in the Data Modeler).

14. What is the purpose of the ABAP Repository Information System? The ABAP Repository Information System allows the retrieval of information about development objects.

15. What are the basic types of queries made to the Repository Information System? -- Find

-- Where-Used

-- Modification analyses (i.e. all objects X modified by user Y)

16. What four basic types of objects can you search for using the R/3 Repository Information System?

Modeling objects, programming objects, ABAP Dictionary objects, and environment objects.

17. What is a foreign key and how is it used?A foreign key is a field that provides a link between two tables by including a reference in the first table (dependent or foreign key table) to the primary key of the second table (check table).

The dependent (foreign key) table may use only those values contained in the check table. The foreign key relationship is set up in the ABAP Dictionary at the field level. The foreign key field and the check table field must have the same domain. An important function of foreign keys is to support data integrity.

18. What is a search help? What are the two stages of creating a collective search help?

A search help is a tool to help find data records stored in the SAP system. It is used as online help (F4) or as a search aid when an entry field calls for a key and only certain other (non-key) fields of the object are known. (i.e. You want to research an employee and know his name but cant remember his personnel number, so a F4 search on his name can help you find the number). First the elementary search helps are defined with the relevant table and fields specified. The collective search help is then defined using multiple elementary search helps.

19. Tables defined in the ABAP Dictionary can be assigned to what 5 specific data classes (via the technical settings screen)?Master data, transaction data, organization and customizing data, system data, and user (customer) data.

20. Name and describe the five table types. Which one is sometimes not considered a true table type?

STRUCTURE (INTTAB): Internal structure without mapping to an underlying database table. Field strings used by ABAP as structures.

Can be used in multiple tables.

TRANSP: SAP data dictionary table that is mapped 1:1 to the database. Designed to hold SAP data in a database.

POOL: Logical pooled table used to store internal control data not relevant externally.

Mapped as many database tables to one SAP table.

CLUSTER: Logical cluster table used to store continuous texts (documentation data).

VIEW: A method of viewing database tables. Can combine data from multiple tables into one view, and/or can restrict the view to certain records or fields within a table. Views are sometimes not considered true table types.

21. What are the four technical settings of a transparent table? Data class: physical area in the database to which the table is assigned.

Size Category: space required for the table in the db (defines the size of the disk space allocated for the table)

Buffering: whether and how to be buffered (suggested for tables not changed very often); tables can have full or partial buffering. Log data changes: (on or off) keeps track of the modifications to a table. If logging is on a copy of data is saved from before changes as well as after.

22. After a table is created, can its technical settings be changed? If so, when?Yes. It is now possible to change the technical settings of an active table and reactivate the table at any time. This is a change from version 2.2 to version 3.0 of SAP.

23. What utility supports the creation of tables and secondary indexes?The database utility. This utility is invoked automatically upon table activation or can be invoked directly from the ABAP Dictionary maintenance screens.

24. What are the possible cardinalities of a foreign key?The relationship is n:m where n refers to the relationship from the foreign key table to the check table and can have values 1 or C (none or 1), and m refers to the relationship from the check table to the foreign key table and can have values 1, C (none or 1), N (1 or many) or CN (none, 1 or many).

The possible cardinalities are 1:1, 1:C, 1:N, 1:CN, C:1, C:C, C:N, and C:CN. The most commonly used cardinalities are 1:1, 1:C, 1:CN, and C:CN.

25. Names of data dictionary objects are limited to how many characters?Restricted to 30. 30 characters are allowed for tables. Search Helps -- 30, logical databases--20, program names -- 40, type groups -- 5.

26. What is the purpose of a type group?Type groups allow the user to define their own data types within the ABAP dictionary. These data types are then available for use in any ABAP program.

Dec-2008Page 5