C_ABAPD_2309 Sample Questions Answers

The expression itab1 = corresponding #( itab2 ) is a constructor expression with the component operator CORRESPONDING that assigns the contents of the internal table itab2 to the internal table itab1. The following statements are true for using this expression:

• B: itab1 and itab2 must have at least one field name in common. This is because the component operator CORRESPONDING assigns the identically named columns of itab2 to the identically named columns of itab1 by default, according to the rules of MOVE-CORRESPONDING for internal tables. If itab1 and itab2 do not have any field name in common, the expression will not assign any value to itab1 and it will remain initial or unchanged1
• C: Fields with the same name and the same type will be copied from itab2 to itab1. This is because the component operator CORRESPONDING assigns the identically named columns of itab2 to the identically named columns of itab1 by default, according to the rules of MOVE-CORRESPONDING for internal tables. If the columns have the same name but different types, the assignment will try to perform a conversion between the types, which may result in a loss of precision, a truncation, or a runtime error, depending on the types involved1

The following statements are false for using this expression:

• A: Fields with the same name but with different types may be copied from itab2 to itab1. This is not true, as explained in statement C. The assignment will try to perform a conversion between the types, which may result in a loss of precision, a truncation, or a runtime error, depending on the types involved1
• D: itab1 and itab2 must have the same data type. This is not true, as the component operator CORRESPONDING can assign the contents of an internal table of one type to another internal table of a different type, as long as theyhave at least one field name in common. The target type of the expression is determined by the left-hand side of the assignment, which is itab1 in this case. The expression will create an internal table of the same type as itab1 and assign it to itab11

References: CORRESPONDING - Component Operator - ABAP Keyword Documentation

The correct expression to change a given string value ‘mr joe doe’ into ‘JOE’ in an ABAP SQL field list is C. SELECT FROM TABLE dbtabl FIELDS Of1, substring(upper(‘mr joe doe’), 4, 3) AS f2_sub_up, f3,… This expression uses the following SQL functions for strings12:

• upper: This function converts all lowercase characters in a string to uppercase. For example, upper(‘mr joe doe’) returns ‘MR JOE DOE’.
• substring: This function returns a substring of a given string starting from a specified position and with a specified length. For example, substring(‘MR JOE DOE’, 4, 3) returns ‘JOE’.
• AS: This keyword assigns an alias or a temporary name to a field or an expression in the field list. For example, AS f2_sub_up assigns the name f2_sub_up to the expression substring(upper(‘mr joe doe’), 4, 3).

You cannot do any of the following:

• A. SELECT FROM TABLE dbtabl FIELDS Of1, upper(left( ‘mr joe doe’, 6)) AS f2_up_left, f3,…: This expression uses the wrong SQL function for strings to get the desired result. The left function returns the leftmost characters of a string with a specified length, ignoring the trailing blanks. For example, left( ‘mr joe doe’, 6) returns ‘mr joe’. Applying the upper function to this result returns ‘MR JOE’, which is not the same as ‘JOE’.
• B. SELECT FROM TABLE dbtabl FIELDS Of1, left(lower(substring( ‘mr joe doe’, 4, 3)), 3) AS f2_left_lo_sub, f3,…: This expression uses unnecessary and incorrect SQL functions for strings to get the desired result. The lower function converts all uppercase characters in a string to lowercase. For example, lower(substring( ‘mr joe doe’, 4, 3)) returns ‘joe’. Applying the left function to this result with the same length returns ‘joe’ again, which is not the same as ‘JOE’.
• D. SELECT FROM TABLE dbtabl FIELDS Of1, substring(lower(upper( ‘mr joe doe’ ) ), 4, 3) AS f2_sub_lo_up, f3,…: This expression uses unnecessary and incorrect SQL functions for strings to get the desired result. The lower function converts all uppercase characters in a string to lowercase, and the upper function converts all lowercase characters in a string to uppercase. Applying both functions to the same string cancels out the effect of each other and returns the original string. For example, lower(upper( ‘mr joe doe’ ) ) returns ‘mr joe doe’. Applying the substring function to this result returns ‘joe’, which is not the same as ‘JOE’.

References: 1: SQL Functions for Strings - ABAP Keyword Documentation - SAP Online Help 2: sql_func - String Functions - ABAP Keyword Documentation - SAP Online Help

An Access Control Object (ACO) is a CDS annotation that defines the access control rules for a CDS view entity. An ACO consists of one or more clauses that specify the role name, the data source, the access conditions, and the return code of the authority check12. Some of the clauses that are used in an ACO are:

• Where (to specify the access conditions): This clause is used to define the logical expression that determines whether a user has access to the data source or not. The expression can use the fields of the data source, the parameters of the CDS view entity, or the predefined variables $user and $session. The expression can also use the functions check_authorization and check_role to perform additional authority checks12.
• Define role (to specify the role name): This clause is used to assign a name to the role that is defined by the ACO. The role name must be unique within the namespace of the CDS view entity and must not contain any special characters. The role name can be used to reference the ACO in other annotations, such as @AccessControl.authorizationCheck or @AccessControl.grant12.
• Revoke (to remove access to the data source): This clause is used to explicitly deny access to the data source for a user who meets the conditions of the where clause. The revoke clause overrides any grant clause that might grant access to the same user. The revoke clause can be used to implement the principle of least privilege or to enforce data segregation12.

You cannot do any of the following:

• Grant (to identify the data source): This is not a valid clause in an ACO. The grant clause is a separate annotation that is used to grant access to a CDS view entity or a data source for a user who has a specific role. The grantclause can reference an ACO by its role name to apply the access conditions defined by the ACO12.
• Return code (to assign the return code of the authority check): This is not a valid clause in an ACO. The return code of the authority check is a predefined variable that is set by the system after performing the access control check. The return code can be used in the where clause of the ACO to specify different access conditions based on the outcome of the check12.

References: 1: Access Control Objects - ABAP Keyword Documentation - SAP Online Help 2: Access Control in Core Data Services (CDS) | SAP Help Portal

The following are the explanations for each statement:

• C: This statement is valid. Class CL1 uses the interface. This is because class CL1 implements the interface ifl using the INTERFACES statement in the public section of the class definition. The INTERFACES statement makes the class compatible with the interface and inherits all the components of the interface. The class can then use the interface components, such as the method ml, by using the interface component selector ~, such as ifl~ml12
• E: This statement is valid. Class CL1 implements the interface. This is because class CL1 implements the interface ifl using the INTERFACES statement in the public section of the class definition. The INTERFACES statement makes the class compatible with the interface and inherits all the components of the interface. The class must then provide an implementation for the interface method ml in the implementation part of the class, unless the method is declared as optional or abstract12
• D: This statement is valid. In class CL2, the interface method is named ifl~ml. This is because class CL2 has a data member named m0_ifl of type REF TO ifl, which is a reference to the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable m0_ifl. The interfacemethod ml has the name ifl~ml in the class, where ifl is the name of the interface and the character ~ is the interface component selector12

The other statements are not valid, as they have syntax errors or logical errors. These statements are:

• A: This statement is not valid. In class CL1, the interface method is named ifl~ml, not if-ml. This is because class CL1 implements the interface ifl using the INTERFACES statement in the public section of the class definition. The interface ifl defines a method ml, which can be called using the class name or a reference to the class. The interface method ml has the name ifl~ml in the class, where ifl is the name of the interface and the character ~ is the interface component selector. Using the character - instead of the character ~ will cause a syntax error12
• B: This statement is not valid. Class CL2 does not use the interface, but only has a reference to the interface. This is because class CL2 has a data member named m0_ifl of type REF TO ifl, which is a reference to the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable m0_ifl. However, class CL2 does not implement the interface ifl, nor does it inherit the interface components. Therefore, class CL2 does not use the interface, but only references the interface12

References: INTERFACES - ABAP Keyword Documentation, CLASS - ABAP Keyword Documentation

Database tables are data structures that store information in two dimensions, using rows and columns. Each row represents a record or an entity, and each column represents an attribute or a field. Database tables may have key fields, which are columns that uniquely identify each row or a subset of rows. Key fields can be used to enforce data integrity, perform efficient searches, and establish relationships to other tables. Database tables can have relationships to other tables, which are associations or links between the key fields of two or more tables. Relationships can be used to model the logical connections between different entities, join data from multiple tables, and enforce referential integrity12.

References: 1: Table (database) - Wikipedia 2: Database design basics - Microsoft Support

Core Data Services (CDS) is a framework for defining and consuming semantically rich data models in SAP HANA. CDS supports various features that enhance the capabilities of SQL and enable developers to create data models that are optimized for performance, readability, and extensibility12. Some of the features of CDS are:

• Associations: Associations are a way of defining relationships between CDS entities, such as tables or views. Associations enable navigation and path expressions in CDS queries, which allow accessing data from related entities without explicit joins. Associations also support cardinality, referential constraints, and cascading options34.
• Annotations: Annotations are a way of adding metadata to CDS entities or their elements, such as fields or parameters. Annotations provide additionalinformation or instructions for the CDS compiler, the database, or the consumers of the CDS views. Annotations can be used for various purposes, such as defining access control, UI rendering, OData exposure, or search capabilities5 .
• Structured Query Language (SQL): SQL is the standard language for querying and manipulating data in relational databases. CDS is based on SQL and extends it with additional features and syntax. CDS supports SQL features such as joins, aggregations, filters, expressions, functions, and subqueries. CDS also supports SQL Script, which is a scripting language for stored procedures and functions in SAP HANA .

You cannot do any of the following:

• Inheritance: Inheritance is not a feature of CDS. Inheritance is a concept in object-oriented programming that allows a class to inherit the properties and methods of another class. CDS does not support object-oriented programming or classes.
• Delegation: Delegation is not a feature of CDS. Delegation is a concept in object-oriented programming that allows an object to delegate some of its responsibilities to another object. CDS does not support object-oriented programming or objects.

References: 1: Core Data Services (CDS) | CAPire 2: Core Data Services [CDS] in SAP S/4 HANA | SAP Blogs 3: Associations in Core Data Services (CDS) | SAP Help Portal 4: [CDS DDL - Association - ABAP Keyword Documentation - SAP Online Help] 5: [Annotations in Core Data Services (CDS) | SAP Help Portal] : [CDS DDL - Annotation - ABAP Keyword Documentation - SAP Online Help] : [Structured Query Language (SQL) | SAP Help Portal] : [CDS DDL - SQL Features - ABAP Keyword Documentation - SAP Online Help] : [Object-Oriented Programming in ABAP | SAP Help Portal]

The annotation that can be used to provide a short description of the data definition for developers that will be attached to the database view is the @EndUserText.label annotation. This annotation is used to specify a text label for the data definition that can be displayed in the development tools or in the documentation. The annotation can be inserted on line #27 in the code snippet provided in the question12. For example:

• The following code snippet uses the @EndUserText.label annotation to provide a short description of the data definition for the CDS view ZCDS_VIEW:

@AbapCatalog.sqlViewName: ‘ZCDS_VIEW’ @AbapCatalog.compiler.compareFilter: true @AbapCatalog.preserveKey: true @AccessControl.authorizationCheck: #CHECK @EndUserText.label: ‘CDS view for flight data’ "short description for developers define view ZCDS_VIEW as select from sflight { key carrid, key connid, key fldate, seatsmax, seatsocc }

You cannot do any of the following:

• @UI.headerInfo.description.label: This annotation is used to specify a text label for the description field of the header information of a UI element. This annotation is not relevant for the data definition of a database view12.
• @UI.badge.title.label: This annotation is used to specify a text label for the title field of a badge UI element. This annotation is not relevant for the data definition of a database view12.
• @EndUserText.quickInfo: This annotation is used to specify a quick information text for the data definition that can be displayed as a tooltip in the development tools or in the documentation. This annotation is not the same as a short description or a label for the data definition12.

References: 1: ABAP CDS - SAP Annotations - ABAP Keyword Documentation - SAP Online Help 2: ABAP CDS - Data Definitions - ABAP Keyword Documentation - SAP Online Help

A projection view is a RESTful Application Programming object that contains only the fields required for a particular app. A projection view is a CDS view entity that defines a projection on an existing CDS view entity or CDS DDIC-based view. A projection view exposes a subset of the elements of the projected entity, which are relevant for a specific business service. A projection view can also define aliases, virtual elements, and annotations for the projected elements. A projection view is the top-most layer of a CDS data model and prepares data for a particular use case. A projection view can have different provider contracts depending on the type of service it supports, such as transactional query, analytical query, or transactional interface.

A database view is a CDS DDIC-based view that defines a join or union of database tables. A database view has an SQL view attached and can be accessed by Open SQL or native SQL. A database view can be used as a projected entity for a projection view, but it does not contain only the fields required for a particular app.

A metadata extension is a RESTful Application Programming object that defines additional annotations for a CDS view entity or a projection view. A metadata extension can be used to enhance the metadata of a CDS data model without changing theoriginal definition. A metadata extension does not contain any fields, but only annotations.

A data model view is a CDS view entity that defines a data model based on database tables or other CDS view entities. A data model view can have associations, aggregations, filters, parameters, and annotations. A data model view can be used as a projected entity for a projection view, but it does not contain only the fields required for a particular app.

References: CDS Projection Views - ABAP Keyword Documentation, CDS Projection Views in ABAP CDS: What’s Your Flavor, Business Object Projection - ABAP Keyword Documentation

The statement that can be used to expose the field “connid” of the data source “demo_ods_assoc_spfli” in the element list is A. demo_ods_assoc_spfli.connid,. This statement uses the dot notation to access the field “connid” of the data source “demo_ods_assoc_spfli”, which is an association defined on line #4. The association “demo_ods_assoc_spfli” links the data source “demo_ods” with the table “spfli” using the field “carrid”. The statement also ends with a comma to separate it from the next element in the list12.

You cannot do any of the following:

• B. demo_ods_assoc_spfli-connid/: This statement uses the wrong syntax to access the field “connid” of the data source “demo_ods_assoc_spfli”. The dash notation is used to access the components of a structure or a table, not the fields of a data source. The statement also ends with a slash, which is not a valid separator for the element list12.
• C. spfli-connid,: This statement uses the wrong data source name to access the field “connid”. The data source name should be “demo_ods_assoc_spfli”,not “spfli”. The statement also uses the wrong syntax to access the field “connid”, as explained above12.
• D. _spfli.connid/: This statement uses the wrong data source name and the wrong separator to access the field “connid”. The data source name should be “demo_ods_assoc_spfli”, not “_spfli”. The statement also ends with a slash, which is not a valid separator for the element list12.

References: 1: ABAP CDS - SELECT, select_list - ABAP Keyword Documentation - SAP Online Help 2: ABAP CDS - SELECT, from - ABAP Keyword Documentation - SAP Online Help

In RESTful Application Programming, a business object contains two main parts: a CDS view and a behavior definition1.

• A. CDS view: A CDS view is a data definition that defines the structure and the data source of a business object. A CDS view can consist of one or more entities that are linked by associations or compositions. An entity is a CDS view element that represents a node or a projection of a business object. An entity can have various annotations that define the metadata and the semantics of the business object2.
• B. Behavior definition: A behavior definition is a source code artifact that defines the behavior and the validation rules of a business object. A behavior definition can specify the standard CRUD (create, read, update, delete) operations, the draft handling, the authorization checks, and the side effects for a business object. A behavior definition can also define custom actions, validations, and determinations that implement the business logic of a business object3.

The following are not parts of a business object in RESTful Application Programming, because:

• C. Authentication rules: Authentication rules are not part of a business object, but part of a service binding. A service binding is a configuration artifact that defines how a business object is exposed as an OData service. A service binding can specify the authentication method, the authorization scope, the protocol version, and the service options for the OData service4.
• D. Process definition: Process definition is not part of a business object, but part of a workflow. A workflow is a business process that orchestrates the tasks and the events of a business object. A workflow can be defined using the Workflow Editor in the SAP Business Application Studio or the SAP Web IDE. A workflow can use the business object’s APIs to trigger or consume events, execute actions, or read or update data5.

References: 1: Business Object | SAP Help Portal 2: CDS View Entities | SAP Help Portal 3: Behavior Definition | SAP Help Portal 4: Service Binding | SAP Help Portal 5: Workflow | SAP Help Portal

The annotation @Environment.systemField: #LANGUAGE is used to assign the ABAP system field sy-langu to an input parameter of a CDS view or a CDS table function. This enables the implicit parameter passing in Open SQL, which means that the value of sy-langu will be automatically passed to the CDS view without explicitly specifying it in the WHERE clause. This also applies to the CDS views that use the annotated CDS view as a data source, which means that the value of sy-langu will be propagated to the nested CDS views (view on view)12. For example:

• The following code snippet defines a CDS view ZI_FLIGHT_TEXTS with an input parameter p_langu that is annotated with @Environment.systemField: #LANGUAGE:

define view ZI_FLIGHT_TEXTS with parameters p_langu : syst_langu @

• The following code snippet shows how to use the CDS view ZI_FLIGHT_TEXTS in ABAP without specifying the value of p_langu in the WHERE clause. The value of sy-langu will be automatically passed to the CDS view:

SELECT carrid, connid, fldate, carrname, carrtext FROM zi_flight_texts INTO TABLE @DATA(lt_flights).

• The following code snippet shows how to use the CDS view ZI_FLIGHT_TEXTS in another CDS view ZI_FLIGHT_REPORT. The value of sy-langu will be automatically passed to the nested CDS view ZI_FLIGHT_TEXTS:

define view ZI_FLIGHT_REPORT with parameters p_langu : syst_langu @

The annotation @Environment.systemField: #LANGUAGE does not prevent the possibility of overriding the default value with a value of your own. You can still specify a different value for the input parameter p_langu in the WHERE clause, either in ABAP or in another CDS view. This will override the value of sy-langu and pass the specified value to the CDS view12. For example:

• The following code snippet shows how to use the CDS view ZI_FLIGHT_TEXTS in ABAP with a specified value of p_langu in the WHERE clause. The value ‘E’ will be passed to the CDS view instead of the value of sy-langu:

SELECT carrid, connid, fldate, carrname, carrtext FROM zi_flight_texts WHERE p_langu = ‘E’ INTO TABLE @DATA(lt_flights).

• The following code snippet shows how to use the CDS view ZI_FLIGHT_TEXTS in another CDS view ZI_FLIGHT_REPORT with a specified value of p_langu in the WHERE clause. The value ‘E’ will be passed to the nested CDS view ZI_FLIGHT_TEXTS instead of the value of sy-langu:

define view ZI_FLIGHT_REPORT with parameters p_langu : syst_langu @

References: 1: ABAP CDS - parameter_annot - ABAP Keyword Documentation - SAP Online Help 2: ABAP CDS - session_variable - ABAP Keyword Documentation - SAP Online Help

The clause in the CDS View Entity Data Definition can be used to specify the data source for the view entity. The clause can accept different types of data sources, depending on the type of the view entity1.

• A database table from the ABAP Dictionary: This is a valid type of data source for a CDS View Entity Data Definition. A database table from the ABAP Dictionary is a table that is defined in the ABAP Dictionary using the keyword TABLE or TABLE OF. The name of the database table must be unique within its namespace and must not contain any special characters2.
• A CDS DDIC-based view: This is also a valid type of data source for a CDS View Entity Data Definition. A CDS DDIC-based view is a view that is defined in the Core Data Services using the keyword DEFINE VIEW ENTITY. The name of the CDS DDIC-based view must be unique within its namespace and must not contain any special characters3.

You cannot do any of the following:

• An external view from the ABAP Dictionary: This is not a valid type of data source for a CDS View Entity Data Definition. An external view from the ABAP Dictionary is a view that is defined in an external application using any language supported by SAP, such as SQL, PL/SQL, or Java. The name of the external view must be unique within its namespace and must not contain any special characters4.
• A database view from the ABAP Dictionary: This is not a valid type of data source for a CDS View Entity Data Definition. A database view from the ABAP Dictionary is a view that is defined in an external application using any language supported by SAP, such as SQL, PL/SQL, or Java. The name of the database view must be unique within its namespace and must not contain any special characters4.

References: 1: CDS DDL - DEFINE VIEW ENTITY - ABAP Keyword Documentation - SAP Online Help 2: ABAP Dictionary Tables - SAP Online Help 3: CDS DDL - DEFINE VIEW ENTITY - ABAP Keyword Documentation - SAP Online Help 4: ABAP Dictionary Views - SAP Online Help

The RESTful Application Programming feature that is used to ensure the uniqueness of a semantic key is determination. A determination is a type of behavior implementation that defines a logic that is executed automatically when certain events occur, such as create, update, delete, or activate. A determination can be used to calculate or derive values for certain fields, such as semantic keys, based on other fields or external sources. A determination can also be used to check the uniqueness of a semantic key by comparing it with the existing values in the database or the transaction buffer. A determination can use the ABAP SQL or the EML syntax to access and manipulate data. A determination can be defined usingthe DETERMINE action clause in the behavior definition of a CDS view entity or a projection view. A determination can also be annotated with the @ObjectModel.determination annotation to specify the event, the timing, and the scope of the determination12

The other RESTful Application Programming features are not used to ensure the uniqueness of a semantic key, but have different purposes and effects. These features are:

• Validation: A validation is a type of behavior implementation that defines a logic that is executed automatically when certain events occur, such as create, update, delete, or activate. A validation can be used to check the consistency and correctness of the data, such as mandatory fields, data types, value ranges, or business rules. A validation can use the ABAP SQL or the EML syntax to access and manipulate data. A validation can be defined using the VALIDATE action clause in the behavior definition of a CDS view entity or a projection view. A validation can also be annotated with the @ObjectModel.validation annotation to specify the event, the timing, and the scope of the validation12
• Action: An action is a type of behavior implementation that defines a logic that is executed explicitly by the user or the application. An action can be used to perform a specific business operation, such as creating, updating, deleting, or activating an entity instance, or triggering a workflow or a notification. An action can use the ABAP SQL or the EML syntax to access and manipulate data. An action can be defined using the ACTION clause in the behavior definition of a CDS view entity or a projection view. An action can also be annotated with the @ObjectModel.action annotation to specify the name, the description, the parameters, and the visibility of the action12

References: Behavior Implementation - ABAP Keyword Documentation, Behavior Definition - ABAP Keyword Documentation

The sequence in which the constructors will be executed is as follows:

• Class constructor of superl. This is because the class constructor is a static method that is executed automatically before the class is accessed for the first time. The class constructor is used to initialize the static attributes and components of the class. The class constructor of the superclass is executed before the class constructor of the subclass, as the subclass inherits the static components of the superclass12
• Class constructor of subl. This is because the class constructor is a static method that is executed automatically before the class is accessed for the first time. The class constructor is used to initialize the static attributes and components of the class. The class constructor of the subclass is executed after the class constructor of the superclass, as the subclass inherits the static components of the superclass12
• Instance constructor of superl. This is because the instance constructor is an instance method that is executed automatically when an instance of the class is created using the statement CREATE OBJECT. The instance constructor is used to initialize the instance attributes and components of the class. The instance constructor of the superclass is executed before the instance constructor of the subclass, as the subclass inherits the instance components of the superclass. The instance constructor of the subclass must call the instance constructor of the superclass explicitly using super->constructor, unless the superclass is the root node object12
• Instance constructor of subl. This is because the instance constructor is an instance method that is executed automatically when an instance of the class is created using the statement CREATE OBJECT. The instance constructor is used to initialize the instance attributes and components of the class. The instance constructor of the subclass is executed after the instance constructor of the superclass, as the subclass inherits the instance components of the superclass. The instance constructor of the subclass must call the instance constructor of the superclass explicitly using super->constructor, unless the superclass is the root node object12

References: Constructors of Classes - ABAP Keyword Documentation, METHODS - constructor - ABAP Keyword Documentation

The code snippet in the image is an example of using the FOR statement to create an internal table with a constructor expression. The FOR statement introduces an iteration expression that runs over the content of source_itab and assigns each row to the variable row. The variable row is then used to populate the fields of target_itab12. Some of the correct statements about the code snippet are:

• FOR defines a loop that runs over the content of source_itab: This is true. The FOR statement iterates over the rows of source_itab and assigns each row to the variable row. The iteration expression can also specify a range or a condition for the loop12.
• row is only visible within the loop: This is true. The variable row is a local variable that is only visible within the scope of the iteration expression. It cannot be accessed outside the loop12.

You cannot do any of the following:

• source_itab is only visible within the loop: This is false. The variable source_itab is not a local variable that is defined by the FOR statement. It is an existing internal table that is used as the data source for the iteration expression. It can be accessed outside the loop12.
• row is a predefined name and cannot be chosen arbitrarily: This is false. The variable row is not a predefined name that is reserved by the FOR statement. It is a user-defined name that can be chosen arbitrarily. However, it must not conflict with any existing names in the program12.

References: 1: FOR - Iteration Expressions - ABAP Keyword Documentation - SAP Online Help 2: ABAP 7.4 Syntax - FOR Loop iteration | SAP Community

The response will be an activation error because the field names of the union do not match. This is because the field names of the union must match in order for the definition to be activated. The union operator combines the result sets of two or more queries into a single result set. The queries that are joined by the union operator must have the same number and type of fields, and the fields must have the same names1. In the given code, the field names of the union do not match, because the first query has the fields carrname, connid, cityfrom, and cityto, while the second query has the fields carrname, carrier_id, cityfrom, and cityto. The field connid in the first query does not match the field carrier_id in the second query. Therefore, the definition cannot be activated.

References: 1: UNION - ABAP Keyword Documentation

 Core Data Services (CDS) are preferable to the classical approach to data modeling for several reasons, but two of them are:

• They implement code pushdown. Code pushdown is the principle of moving data-intensive logic from the application server to the database server, where the data resides. This reduces the data transfer between the application server and the database server, which improves the performance and scalability of the application. CDS enable code pushdown by allowing the definition of semantic data models and business logic in the database layer, using SQL and SQL-based expressions1.
• They transfer computational results to the application server. CDS allow the application server to access the data and the logic defined in the database layer by using Open SQL statements. Open SQL is a standardized and simplified subset of SQL that can be used across different database platforms. Open SQL statements are translated into native SQL statements by the ABAP runtime environment and executed on the database server. The results of the computation are then transferred to the application server, where they can be further processed or displayed2.

References: 1: ABAP - Core Data Services (ABAP CDS) - ABAP Keyword Documentation 2: Open SQL - ABAP Keyword Documentation

The statement that can be used to change the contents of a row of data in an internal table is MODIFY table. The MODIFY table statement can be used to change the contents of one or more rows of an internal table, either by specifying the table index, the table key, or a condition. The MODIFY table statement can also be used to change the contents of a database table, by specifying the table name and a work area or an internal table. The MODIFY table statement can use the TRANSPORTING addition to specify which fields should be changed, and the WHERE addition to specify which rows should be changed.

The other statements are not suitable for changing the contents of a row of data in an internal table, as they have different purposes and effects. These statements are:

• APPEND table: This statement can be used to add a new row of data to the end of an internal table, either by specifying a work area or an inline declaration. The APPEND table statement does not change the existing rows of the internal table, but only increases the number of rows by one.
• INSERT table: This statement can be used to insert a new row of data into an internal table, either by specifying the table index, the table key, or a sorted position. The INSERT table statement does not change the existing rows of the internal table, but only shifts them to make room for the new row. The INSERT table statement can also be used to insert a new row of data into a database table, by specifying the table name and a work area or an inline declaration.
• UPDATE table: This statement can be used to update the contents of a database table, by specifying the table name and a work area or an internal table. The UPDATE table statement can use the SET addition to specify which fields should be updated, and the WHERE addition to specify which rows should be updated. The UPDATE table statement does not affect the internal table, but only the corresponding database table.

References: MODIFY table - ABAP Keyword Documentation, APPEND table - ABAP Keyword Documentation, INSERT table - ABAP Keyword Documentation, UPDATE table - ABAP Keyword Documentation

In RESTful Application Programming, the EML statement that retrieves an object is GET entity. The GET entity statement is used to read data of an entity instance from the database or the transaction buffer. The GET entity statement can specify the entity name, the entity key, and the entity elements to be retrieved. The GET entity statement can also use the IN LOCAL MODE addition to bypass the access control, authorization control, and feature control checks. The GET entity statement returns a single entity instance or raises an exception if no instance is found or multiple instances match the key.

The other EML statements are not used to retrieve an object, but have different purposes and effects. These statements are:

• FIND entity: This statement is used to search for entity instances that match a given condition. The FIND entity statement can specify the entity name, the entity elements to be returned, and the condition to be applied. The FIND entity statement can also use the IN LOCAL MODE addition to bypass the access control, authorization control, and feature control checks. The FIND entity statement returns a table of entity instances or an empty table if no instances match the condition.
• SELECT entity: This statement is used to query data of entity instances from the database or the transaction buffer. The SELECT entity statement can specify the entity name, the entity elements to be returned, and the filter, order, and aggregation options to be applied. The SELECT entity statement can also use the IN LOCAL MODE addition to bypass the access control, authorization control, and feature control checks. The SELECT entity statement returns a table of entity instances or an empty table if no instances match the query.
• READ entity: This statement is not a valid EML statement, but an ABAP statement. The READ statement is used to access a single row of an internal table using the table index or the table key. The READ statement can also use the TRANSPORTING addition to specify which fields should be returned, and the INTO addition to specify the target variable. The READ statement returns a single row of the internal table or raises an exception if no row is found or multiple rows match the key.

References: GET ENTITY - ABAP Keyword Documentation, FIND ENTITY, ENTITIES - ABAP Keyword Documentation, SELECT ENTITY, ENTITIES - ABAP Keyword Documentation, READ - ABAP Keyword Documentation

The following are the explanations for each statement:

• A: This statement is valid. go_ifl may call method ml with go_ifl->ml(). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable go_ifl. The class cll implements the interface ifl, which means that it provides an implementation of the method ml. The data object go_ifl is assigned to a new instance of the class cll using the NEW operator and the inline declaration operator @DATA. Therefore, when go_ifl->ml() is called, the implementation of the method ml in the class cll is executed123
• B: This statement is valid. Instead of go_cll = NEW #(…) you could use go_ifl = NEW cll(…). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The class cll implements the interface ifl, which means that it is compatible with the interface ifl. Therefore, go_ifl can be assigned to a new instance of the class cll using the NEW operator and the class name cll. The inline declaration operator @DATA is optional in this case, as go_ifl is already declared. The parentheses after the class name cll can be used to pass parameters to the constructor of the class cll, if any123
• E: This statement is valid. go_ifl may call method m2 with go_ifl->m2(…). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The class cll implements the interface ifl, which means that it inherits all the components of the interface ifl. The class cll also defines amethod m2, which is a public method of the class cll. Therefore, go_ifl can call the method m2 using the reference variable go_ifl. The method m2 is not defined in the interface ifl, but it is accessible through the interface ifl, as the interface ifl is implemented by the class cll. The parentheses after the method name m2 can be used to pass parameters to the method m2, if any123

The other statements are not valid, as they have syntax errors or logical errors. These statements are:

• C: This statement is not valid. go_cll may call method ml with go_cll->ifl~ml(). This is because go_cll is a data object of type REF TO cll, which is a reference to the class cll. The class cll implements the interface ifl, which means that it inherits all the components of the interface ifl. The interface ifl defines a method ml, which can be called using the reference variable go_cll. However, the syntax for calling an interface method using a class reference is go_cll->ml(), not go_cll->ifl~ml(). The interface component selector ~ is only used when calling an interface method using an interface reference, such as go_ifl->ifl~ml(). Using the interface component selector ~ with a class reference will cause a syntax error123
• D: This statement is not valid. Instead of go_cll = NEW #() you could use go_ifl = NEW #(…). This is because go_ifl is a data object of type REF TO ifl, which is a reference to the interface ifl. The interface ifl cannot be instantiated, as it does not have an implementation. Therefore, go_ifl cannot be assigned to a new instance of the interface ifl using the NEW operator and the inline declaration operator @DATA. This will cause a syntax error or a runtime error. To instantiate an interface, you need to use a class that implements the interface, such as the class cll123

References: INTERFACES - ABAP Keyword Documentation, CLASS - ABAP Keyword Documentation, NEW - ABAP Keyword Documentation

The access to internal tables can be optimized by using the appropriate table type and specifying the table key. The table key is a set of fields that uniquely identifies a row in the table and determines the sorting order of the table. The table key can be either the primary key or a secondary key. The primary key is defined by the table type and the table definition, while the secondary key is defined by the user using the KEY statement1.

The following results in faster access to internal tables:

• B. In a sorted internal table, specifying the primary key completely. A sorted internal table is a table type that maintains a predefined sorting order, which is defined by the primary key in the table definition. The primary key can be either unique or non-unique. A sorted internal table can be accessed using the primary key or the table index. The access using the primary key is faster than the access using the table index, because the system can use a binary search algorithm to find the row. However, the primary key must be specified completely, meaning that all the fields of the primary key must be given in the correct order and without gaps2.
• D. In a hashed internal table, specifying the primary key partially from the left without gaps. A hashed internal table is a table type that does not have a predefined sorting order, but uses a hash algorithm to store and access the rows. The primary key of a hashed internal table must be unique and cannot be changed. A hashed internal table can only be accessed using the primary key, not the table index. The access using the primary key is very fast, because the system can directly calculate the position of the row using the hash algorithm. The primary key can be specified partially from the left without gaps, meaning that some of the fields of the primary key can be omitted, as long as they are the rightmost fields and there are no gaps between the specified fields.
• E. In a hashed internal table, specifying the primary key completely. A hashed internal table is a table type that does not have a predefined sorting order, but uses a hash algorithm to store and access the rows. The primary key of a hashed internal table must be unique and cannot be changed. A hashed internal table can only be accessed using the primary key, not the table index. The access using the primary key is very fast, because the system can directly calculate the position of the row using the hash algorithm. The primary key can be specified completely, meaning that all the fields of the primary key must be given in the correct order.

The following do not result in faster access to internal tables, because:

• A. In a sorted internal table, specifying the primary key partially from the left without gaps. A sorted internal table is a table type that maintains a predefined sorting order, which is defined by the primary key in the table definition. The primary key can be either unique or non-unique. A sorted internal table can be accessed using the primary key or the table index. The access using the primary key is faster than the access using the table index, because the system can use a binary search algorithm to find the row. However, the primary key must be specified completely, meaning that all the fields of the primary key must be given in the correct order and without gaps. If the primary key is specified partially from the left without gaps, the system cannot use the binary search algorithm and has to perform a linear search, which is slower2.
• C. In a standard internal table, specifying the primary key partially from the left without gaps. A standard internal table is a table type that does not have a predefined sorting order, but uses a sequential storage and access of the rows. The primary key of a standard internal table is the standard key, which consists of all the fields of the table row in the order in which they are defined. A standard internal table can be accessed using the primary key or the table index. The access using the primary key is slower than the access using the table index, because the system has to perform a linear search to find the row. The primary key can be specified partially from the left without gaps, but this does not improve the access speed, because the system still has to perform a linear search.

References: 1: Internal Tables - Overview - ABAP Keyword Documentation 2: Sorted Tables - ABAP Keyword Documentation : Hashed Tables - ABAP Keyword Documentation : Standard Tables - ABAP Keyword Documentation