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Saturday, April 21, 2012

SAP ABAP Data Dictionary Interview Questions






Dear ABAPers, This post gives the list of Interview questions on SAP ABAP. The list includes the real time interview questions asked by the top MNC companies in their interviews. For more details refer this post. SAP Interview Questions.






ABAP Data dictionary interview questions


Q. What’s the full form of ECC?


Ans: Enterprice Central Component.




Q. What’s the full form of IDES?


Ans: Internet Demonstration and Evaluation System.




Q. What’s ABAP dictionary and its role in SAP?


Ans: ABAP dictionary is the central information base for the developers. This manages all definitions(metadata) required for different applications in SAP. ABAP dictionary is completely integrated into ABAP development workbench. All other component of ABAP development workbench can access the data definitions(meta data) stored in the data dictionary.




Role: ABAP data dictionary supports
  • definition of user-defined types (data elements, structures, table types).
  • structure of database objects (tables, indexes and views) can also be defined.
    These user-defined types/objects are then automatically created in the underlying relational database using the above data definitions.
  • The ABAP dictionary also provides tools for editing screen fields (e.g., for assigning a field an input help i.e. F4 help).
  • Data dictionary ensures data integrity, consistency and security.
Q. What are the main object types of ABAP dictionary?


Ans: The object types of ABAP dictionary can be of following type:
  • Tables: Tables are defined in the ABAP Dictionary independently of the database.
    A table having the same structure is then created from this table definition in the underlying database.
  • Views: are logical views on more than one table. The structure of the view is defined in the ABAP Dictionary. A view on the database can then be created from this structure.
  • Types (elements, structures, table types): Types are created in ABAP programs. The structure of a type can be defined globally in ABAP programs. Changes to a type automatically take effect in all the programs using the type.
  • Lock objects:are used to synchronize access to the same data by more than one user. Function modules that can be used in application programs are generated from the definition of a lock object in the ABAP Dictionary.
  • Domains: Different fields having the same technical type can be combined in domains. Domain defines the value range of all table fields and structure components that refer to this domain.
  • Data element: The ABAP Dictionary also contains the information displayed with the F1 and F4 help for a field in an input template. The documentation about the field is created for a data element.
  • Input help: The list of possible input values that appears for the input help is created by a foreign key or a search help.


Q. Note on SAP tables(defining through ABAP dictionary).
Ans: Tables are defined independently of the database in ABAP dictionary. The fields of the table are defined with their (Database-independent) data types and lengths. Using the table definitions stored in the ABAP dictionary, a table is automatically created in the physical database(when the table is activated).




Q. What are the components of a table definition.
Ans:
  • Table fields: For table fields, field names and data types are defined.
  • Foreign keys: Relationship between the table and the other tables are defined.
  • Technical settings: Data class and size category defines that what type of table
    to be created and how much space required.
  • Indexes: Secondary indexes are created for a table for faster data selection.
Again following are defined for a table fields:
  • Field name can be of maximum 16 characters in a table and must start with a letter.
  • Key flag determines if a field should be the table key.
  • Field type depicts the data type of the field in the ABAP dictionary.
  • Field length denotes the number of valid places in the field.
  • Decimal places Number of places after decimal point for float type value.
  • Short text describes the business meaning of the field.
Also fields from other structures can be added to the table definition as include.




Q. How data Type, field Length and short Text of any field is assigned?
Ans: i. Data type, field length (and if necessary decimal places) short text can be directly assigned to a field in the table definition.
ii. Data element can be assigned to a field so that data type, field length (and decimal places) are automatically determined from the domain of the data element. The short description of the data element is then assigned to the field as a short text.





Q. What are the assignment options to the field?
Ans: i. Direct assignment of data types, field length, short text to a field.
ii. Data element assignment to a field.
iii. An input check(check table) for a field can be defined with a foreign key.
iv. A search help can be assigned to a field.
v. Reference field or reference table must be specified for a table field that holds currency or quantity type value.




Q. What’s reference table and reference field?
Ans: Reference table is specified for fields containing quantities(data type QUAN) or currency(Data type CURR). This reference table must contain a field with the format for the currency key (data type CUKY) or unit of measure (data type UNIT). This field is called the reference field of the output field. The reference field can also reside in the table itself.

E.g.: TAB1 contains the field PRICE which holds price values. Field UNIT contains currency key for PRICE.
So,TAB1 is the reference table for field PRICE and UNIT is the reference field for field PRICE.





Q. What’s table include?
Ans: In addition to listing the individual fields in a table or structure, fields from another structure can be included as includes.




Q. What’s named include?
Ans: If an include is added to define a database table or database structure, a name can be assigned to that included (included substructure). The group of fields of that include can be addressed as a whole in ABAP application programs with a group name which is called as named include.
E.g.:We can access field of a table/ structure in the ABAP application program in the following manner:
  1. <TABLE / STRUCTURE NAME > - < FIELD NAME>
  2. <TABLE / STRUCTURE NAME > - <GROUP NAME>-<FIELD NAME>
  3. <TABLE / STRUCTURE NAME > - <GROUP NAME>




Q. Give an example of nested include.
Ans: Structure S1 may include structure S2 and again S2 may include S3.




Q.What’s the maximum depth of nested includes in a table?
A
ns: Maximum depth is 9 i.e. maximum 9 structures can be included in a table/structure.




Q. What’s the number of characters limit for field name?
Ans: A field name may not have more than 16 characters in a table, but in a structure maximum 30 characters are allowed for a field name.





Q. What are foreign keys?
Ans: Relationships between tables are defined in the ABAP dictionary by creating foreign keys.




Q. Whare are the uses of foreign keys in SAP?
Ans:
  • Using foreign keys(as main table-field is linked with check table), input value check for any input field can be done.
  • Foreign keys can also be used to link several tables.
Explaination on foreign keys:

Suppose, tab1(Foreign key table or dependent table) contains the following fields: fld1(primary key), fld2, fld3, fld4, fld5 and Tab2(Referenced table) contains the following fields: fld6(primary key), fld7(primary key), fld8, fld9 and tab1-fld2 is connected to tab2-fld5, tab1-fld4 is connected to tab2-fld6Therefore, fld2 and fld4 fields of the table tab1 are called as foreign key fields to the table tab2 and tab2 is called as check table or referenced table.




Q. What are foreign key fields?
Ans: One field of the foreign key table corresponds to each key field of the check table. That field of the is called as foreign key field.
Uses: A foreign key permits assigning data records in the foreign key table and check table. One record of the foreign key table uniquely identifies a record of the check table (using the value entries in the foreign key fields of the foreign key table).




Q. What’s check table?
Ans: Check table is maintained at field level for data validation.




Q. What’s check field?
Ans: One of the foreign key field is marked as the check field. This depicts that the foreign key relationship is maintained for that field. When a value is entered for that check field in the table, input validation checking is done i.e. a checking is done that whether the inserted value exists in the check table or not. If doesn’t exist then system rejects the entry else input validation check for that field is successful.

Q. What’s generic and constant foreign keys?



Q. What’s cardinality?


Q. What are the types of foreign key fields?


Q. What are text table?


Q. What is ‘technical settings’ of a table?What are the important parameters to be mentioned within it?




Q. What’s data class?
Ans: Data class is that which allows the table to get automatically assigned under specific tablespace/dbspace during table creation in the SAP database i.e. dataclass determines that under which table space/dbspace the table will be stored.




Q. How many types of data classes are there in SAP?
Data classes are mainly of three types(for application tables):


i.Choose APPL0(master data) for data that is frequently accessed but rarely updated/changed.


ii.Choose APPL1(transaction data) for data that is frequently changed.


iii.Choose APPL2(organizational data) for customizing data that is defined/entered during system installation and rarely changed.




The other two types of data classes are:USR and USR1(for customer’s own development purpose).




Q. What’s size category?
Ans: The Size category is used to defined the space requirement for the table in the database.




Q. How many types of size category are there in SAP?
Ans: There are five size categories. Size category from 0 to 4 can be choosen for the tables. A certain fixed memory size is assigned to each category in the SAP database.




Q. What’s the utility of size category?
Ans: During table creation, the SAP system reserves an initial space i.e. an initial extent) in the database.If in any case more space is needed, then additional memory is added according to the mentioned size category for that table. correct size category prevents the creation of a large number of small extents for a table i.e. prevents memory wastage.



Q. What’s buffering?




Q. How buffers are filled up?




Q. What are the different buffering types?




Q. What are the different buffering permissions?




Q. How database tables are buffered?




Q. What’s logging?




Q. How many tables are there in SAP?
Ans: i. Transparent tables, ii. Pool tables, iii. Cluster tables.




Q. What is transparent table?
Ans: The tables which create 1-to-1 correspondence between the table definition in the ABAP data dictionary and the table definition in the physical database are called as transparent tables in SAP.




Q. Give examples of transparent table.
Ans: VBAK, VBAP, KNA1 etc.




Q. What is table pool?
Ans: Table pool is a table in the SAP database in which many pool tables are assigned.




Q. What are pool tables?
Ans: Tables assigned to a table pool are called as pool tables.




Q. What are table clusters?
Ans: Table cluster is a table in the SAP database in which many cluster tables are stored.




Q. What are clustered tables?
Ans: Tables assigned to a Table cluster are called as clustered tables.




Q. Uses of table pool or table cluster.
Ans: Table pool or table cluster is used to store SAP’s internal control information (screen sequences, program parameters, temporary data, continuous texts such as documentation).




Q. Example of table cluster and cluster tables.
Ans: 
i. The table cluster RFBLG holds data for five transparent tables i.e. BSEC, BSED, BSEG, BSES and BSET.


ii. Other examples of table clusters are CDCLS, CDHDR, RFBLG, DOKCLU, DOKTL .




Q. What are the differences between transparent and cluster/pool tables?
Ans: 


i. A transparent table has 1-to-1 cardinality between the table definition in the data dictionary and in the table definition of sap database whereas cluster/pool tables have many-to-1 cardinality between the table definition in the data dictionary and in the table definition of sap database.


ii. Transparent tables are accessible both by Open and native SQL statements whereas table pool/cluster tables are accessible only by open SQL but never by native SQL.


iii. Transparent tables can store table relevant data whereas table pool or cluster tables can store only system data/ application data based on the transparent tables.




Q. What are tabs under the maintenance screen of the ABAP data dictionary screen?


Ans: There are five tabs under ABAP dictionary.


i.Attributes,


ii.Delivery & maintenance,


iii. Fields,


iv. Entry help/check,


v. Currency/Quantity fields.




Q. What is delivery class?


Ans: We need to insert an delivery class value while creating customized table in SAP through the transaction code SE11. 


Delivery class is that which regulates the transport of the table’s data records (during SAP installations, SAP software upgrade, client copies, and data transport to other SAP system). SAP and its customers have different write types depending on the variety of delivery class. If Delivery class is A, it depicts that the application table for master and transaction data changes only rarely.




Q. How many types of delivery classes are there in SAP?
Ans: There are following delivery classes:


i. A: Application table (master and transaction data) is maintained by the customers using application transaction.




ii. C: Customer table. Data is maintained only by the customer.




iii. L: Table for storing temporary data.




iv. G: Customer table, new data records can be inserted but may not overwrite or delete existing ones.


v. E: System table with its own namespaces for customer entries.


vi. S: System table, data changes have the status of program changes i.e. System table for program’s nature. Maintained only by SAP. E.g.: Codes for SAP transactions.


vii. W: System table for system operation and maintenance. Table contents are maintained by maintenance transactions. E.g.: function module table.


Q. What are the differences between domain and data element?
Ans: 


i.Domain depicts the technical attributes of a field (its data type, field length, no. of decimal places, appreance on the sreen) of a SAP database table. Whereas data element denotes the semantic attributes(short description, label names) for a field.


ii.Data elements are directly attaced to the fields of SAP database tables and each data element has an underlying domain within it. Whereas domains are not directly attached to the fields and a single domain can be under many data elements.


iii.Within domain value range of a field can be described. Whereas within the data element parameter id and search help for a particular field can be assigned.




Q. What’s value table?


Ans: Value table is maintained at domain level in SAP. During domain creation, value range of the domain is defined by specifying value table. Suppose for a particular domain, its value table holds the values ‘A’, ‘B’, ‘Z’. So whenever the domain will be used, system will allow to use these values only.

Re: How you can perform field-validation in your dialog program ? Answer

You can validate your fields in the PAI module of the program by placing them between the CHAIN & ENDCHAIN Statement.

Re: HOW MANY EDITORS ARE THERE IN SAP ABAP. WHAT ARE THEY AND THERE USES. 

Answer
There r 3 types of editors.

 1. ABAP Editor------> SE38.

 2. Screen Editor----> SE51.

 3. Script Editor----> Se71.






For More Real Time Interview Questions See Below Posts















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