C_ABAPD_2309 SAP Certified Associate - Back-End Developer - ABAP Cloud Question and Answers

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 predicate condition that can be used to ensure that the CAST will work is IS INSTANCE OF. The IS INSTANCE OF predicate condition checks whether the operand is an instance of the specified class or interface. This is useful when you want to perform a downcast, which is a conversion from a more general type to a more specific type. A downcast can fail if the operand is not an instance of the target type, and this can cause a runtime error. Therefore, you can use the IS INSTANCE OF predicate condition to check whether the downcast is possible before using the CAST operator12. For example:

• The following code snippet uses the IS INSTANCE OF predicate condition to check whether the variable g_super is an instance of the class lcl_super. If it is, the CAST will work and the variable g_sub1 will be assigned the value of g_super.

DATA: g_super TYPE REF TO lcl_super, g_sub1 TYPE REF TO lcl_sub1. IF g_super IS INSTANCE OF lcl_super. g_sub1 = CAST #( g_super ). g_sub1->method( … ). ENDIF.

You cannot do any of the following:

• IS SUPPLIED: The IS SUPPLIED predicate condition checks whether an optional parameter of a method or a function module has been supplied by the caller. This is useful when you want to handle different cases depending on whether the parameter has a value or not. However, this predicate condition has nothing to do with the CAST operator or the type of the operand12.
• IS NOT INITIAL: The IS NOT INITIAL predicate condition checks whether the operand has a non-initial value. This is useful when you want to check whether the operand has been assigned a value or not. However, this predicate condition does not guarantee that the CAST will work, because the operand may have a value but not be an instance of the target type12.
• IS BOUND: The IS BOUND predicate condition checks whether the operand is a bound reference variable. This is useful when you want to check whether the operand points to an existing object or not. However, this predicate condition does not guarantee that the CAST will work, because the operand may point to an object but not be an instance of the target type12.

References: 1: Predicate Expressions - ABAP Keyword Documentation - SAP Online Help 2: ABAP - Predicates | SAP Community

 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

After you created a database table in the RESTful Application Programming model (RAP), the next step is to create a projection view on the database table. A projection view is a CDS artefact that defines a view on one or more data sources, such as tables, views, or associations. A projection view can select, rename, or aggregate the fields of the data sources, but it cannot change the properties of the fields, such as whether they are read-only or not. The properties of the fields are inherited from the data sources or the behaviour definitions of the business objects12. For example:

• The following code snippet defines a projection view ZI_AGENCY on the database table /DMO/AGENCY:

define view ZI_AGENCY as select from /dmo/agency { key agency_id, agency_name, street, city, region, postal_code, country, phone_number, url }

The projection view is used to expose the data of the database table to the service definition, which is the next step in the RAP. The service definition is a CDS artefact that defines the interface and the binding of a service. A service is a CDS entity that exposes the data and the functionality of one or more business objects as OData, InA, or SQL services. A service definition can specify the properties of the fields of a service, such as whether they are filterable, sortable, or aggregatable12. For example:

• The following code snippet defines a service definition ZI_AGENCY_SRV that exposes the projection view ZI_AGENCY as an OData service:

define service ZI_AGENCY_SRV { expose ZI_AGENCY as Agency; }

You cannot do any of the following:

• A. A metadata extension: A metadata extension is a CDS artefact that defines additional annotations for a CDS entity, such as a business object, a service, or a projection view. A metadata extension can specify the properties of the fields of a CDS entity for UI or analytical purposes, such as whether they are visible, editable, or hidden. However, a metadata extension is not the next step after creating a database table in the RAP, as it is not required to expose the data of the database table to the service definition. A metadata extension can be created later to customize the UI or analytical application that uses the service12.
• C. A data model view: A data model view is a CDS artefact that defines a view on one or more data sources, such as tables, views, or associations. A data model view can select, rename, or aggregate the fields of the data sources, and it can also change the properties of the fields, such as whether they are read-only or not. The properties of the fields are defined by the annotations or the behaviour definitions of the data model view. A data model view is used to define the data model of a business object, which is a CDS entity that represents a business entity or concept, such as a customer, an order, or a product. However, a data model view is not the next step after creating a database table in the RAP, as it is not required to expose the data of the database table to the service definition. A data model view can be created later to define a business object that uses the database table as a data source12.
• D. A service definition: A service definition is a CDS artefact that defines the interface and the binding of a service. A service is a CDS entity that exposes the data and the functionality of one or more business objects as OData, InA, or SQL services. A service definition can specify the properties of the fields of a service, such as whether they are filterable, sortable, or aggregatable. However, a service definition is not the next step after creating a database table in the RAP, as it requires a projection view or a data model view to expose the data of the database table. A service definition can be created after creating a projection view or a data model view on the database table12.

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

On-stack developer extensibility is a type of extensibility that allows you to create development projects directly on the SAP S/4HANA Cloud technology stack. It gives you the opportunity to develop cloud-ready and upgrade-stable custom ABAP applications and services inside the SAP S/4HANA Cloud, public edition system. You can use the ABAP Development Tools in Eclipse to create and deploy your on-stack extensions. On-stack developer extensibility is suitable for the following kinds of applications:

• Applications that provide APIs for side by side SAP BTP apps. On-stack developer extensibility allows you to create OData services or RESTful APIs based on CDS view entities or projection views. These services or APIs can expose SAP S/4HANA data and logic to other applications that run on the SAP Business Technology Platform (SAP BTP) or other platforms. This way, you can create a loosely coupled integration between your SAP S/4HANA system and your side by side SAP BTP apps.
• Applications that access SAP S/4HANA data using complex SQL. On-stack developer extensibility allows you to use ABAP SQL to access SAP S/4HANA data using complex queries, such as joins, aggregations, filters, parameters, and code pushdown techniques. You can also use ABAP SQL to perform data manipulation operations, such as insert, update, delete, and upsert. This way, you can create applications that require advanced data processing and analysis on SAP S/4HANA data.

The other kinds of applications are not suitable for on-stack developer extensibility, as they have different requirements and challenges. These kinds of applications are:

• Applications that integrate data from several different systems. On-stack developer extensibility is not meant for creating applications that integrate data from multiple sources, such as other SAP systems, third-party systems, or cloud services. This is because on-stack developer extensibility does not support remote access or data replication, and it may cause performance or security issues. For this kind of applications, you should use side by side extensibility, which allows you to create applications that run on the SAP BTP and communicate with the SAP S/4HANA system via public APIs or events.
• Applications that run separate from SAP S/4HANA. On-stack developer extensibility is not meant for creating applications that run independently from the SAP S/4HANA system, such as standalone apps, microservices, or web apps. This is because on-stack developer extensibility requires a tight coupling with the SAP S/4HANA system, and it may limit the scalability, flexibility, and portability of the applications. For this kind of applications, you should use side by side extensibility, which allows you to create applications that run on the SAP BTP and leverage the cloud-native features and services of the platform.

References: Developer Extensibility in SAP S/4HANA Cloud ABAP Environment, SAP S/4HANA Extensibility – Simplified Guide for Beginners

In ABAP SQL, the syntax to retrieve the association field of a CDS view is to use the @ sign followed by the association name and the field name, separated by a period sign (.). For example, to retrieve the association field _Airline-Name of a CDS view, the syntax is @_Airline.Name. This syntax allows the access to the fields of the target data source of the association without explicitly joining the data sources1. The other options are incorrect because they use the wrong symbols or formats to access the association field.

References: 1: Path Expressions - 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

The data declarations that will always work without truncation or rounding for the assignment gv_target = gv_source are B and C. This is because the target data type string is a variable-length character type that can hold any character string, including those of data types c (fixed-length character) and d (date). The assignment of a character or date value to a string variable will not cause any loss of information or precision, as the string variable will adjust its length to match the source value12.

You cannot do any of the following:

• A. DATA gv_source TYPE string, to DATA gv_target TYPE c.: This data declaration may cause truncation for the assignment gv_target = gv_source. This is because the target data type c is a fixed-length character type that has a predefined length. If the source value of type string is longer than the target length of type c, the source value will be truncated on the right to fit the target length12.
• D. DATA gv_source TYPE p LENGTH 8 DECIMALS 3. to DATA gv_target TYPE p LENGTH 16 DECIMALS 2.: This data declaration may cause rounding for the assignment gv_target = gv_source. This is because the target data type p is a packed decimal type that has a predefined length and number of decimal places. If the source value of type p has more decimal places than the target type p, the source value will be rounded to the target number of decimal places12.

References: 1: ABAP Data Types - ABAP Keyword Documentation - SAP Online Help 2: ABAP Assignment Rules - ABAP Keyword Documentation - SAP Online Help

The purpose of a foreign key relationship between two tables in the ABAP Dictionary is to ensure the integrity of data in the corresponding database tables. A foreign key relationship defines a logical link between a foreign key table and a check table, where the foreign key fields of the former are assigned to the primary key fields of the latter. This means that the values entered in the foreign key fields must exist in the check table, otherwise the system will reject the entry. This way, the foreign key relationship prevents the insertion of invalid or inconsistent data in the database tables.

A foreign key relationship also serves to document the relationship between the two tables in the ABAP Dictionary, but this is not its primary purpose. A foreign key relationship does not necessarily create a corresponding foreign key relationship in the database, as this depends on the database system and the settings of the ABAP Dictionary. Some database systems do not support foreign keys at all, while others require additional steps to activate them. Therefore, the foreign key relationship in the ABAP Dictionary is mainly a logical concept that is enforced by the ABAP runtime environment.

References: Foreign Keys (SAP Library - ABAP Dictionary), Foreign Keys (SAP Library - BC - ABAP Dictionary)

https://help.sap.com/doc/saphelp_snc70/7.0/en-US/cf/21ea77446011d189700000e8322d00/content.htm

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 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 a method 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

Based on the given information, the spfli database table should have the following general settings:

• “Storage Type” to “Row Store”: This setting determines how the data is stored in the SAP HANA database. Row store is suitable for tables that are accessed by primary key or by a small number of columns. Column store is suitable for tables that are accessed by a large number of columns or by complex analytical queries. Since the spfli table is a large table with over one million rows, and this program is the only one in the system that accesses the table, it is likely that the program will use primary key access or simple queries to access the table. Therefore, row store is a better choice than column store for this table12.
• “Load Unit” to “Page Loadable”: This setting determines how the data is loaded into the memory when the table is accessed. Page loadable means that the data is loaded in pages of 16 KB each, and only the pages that are needed are loaded. Column loadable means that the data is loaded in columns, and only the columns that are needed are loaded. Since the spfli table is a row store table, and this program will run rarely, it is more efficient to use page loadable than column loadable for this table. Page loadable will reduce the memory consumption and the loading time of the table13.

References: 1: Table Types in SAP HANA | SAP Help Portal 2: [Row Store vs Column Store in SAP HANA | SAP Blogs] 3: [Load Unit | SAP Help Portal]

Secondary keys are additional keys that can be defined for internal tables to optimize the access to the table using fields that are not part of the primary key. Secondary keys can be either sorted or hashed, depending on the table type and the uniqueness of the key. Secondary keys have the following characteristics1:

• A. Secondary keys must be chosen explicitly when you actually read from an internal table. This means that when you use a READ TABLE or a LOOP AT statement to access an internal table, you have to specify the secondary key that you want to use with the USING KEY addition. For example, the following statement reads an internal table itab using a secondary key sec_key:

READ TABLE itab USING KEY sec_key INTO DATA(wa).

If you do not specify the secondary key, the system will use the primary key by default2.

• B. Multiple secondary keys are allowed for any kind of internal table. This means that you can define more than one secondary key for an internal table, regardless of the table type. For example, the following statement defines an internal table itab with two secondary keys sec_key_1 and sec_key_2:

DATA itab TYPE SORTED TABLE OF ty_itab WITH NON-UNIQUE KEY sec_key_1 COMPONENTS field1 field2 sec_key_2 COMPONENTS field3 field4.

You can then choose which secondary key to use when you access the internal table1.

• D. Sorted secondary keys do NOT have to be unique. This means that you can define a sorted secondary key for an internal table that allows duplicate values for the key fields. A sorted secondary key maintains a predefined sorting order for the internal table, which is defined by the key fields in the order in which they are specified. For example, the following statement defines a sorted secondary key sec_key for an internal table itab that sorts the table by field1 in ascending order and field2 in descending order:

DATA itab TYPE STANDARD TABLE OF ty_itab WITH NON-UNIQUE SORTED KEY sec_key COMPONENTS field1 ASCENDING field2 DESCENDING.

You can then access the internal table using the sorted secondary key with a binary search algorithm, which is faster than a linear search3.

The following are not characteristics of secondary keys for internal tables, because:

• C. Hashed secondary keys do NOT have to be unique. This is false because hashed secondary keys must be unique. This means that you can only define a hashed secondary key for an internal table that does not allow duplicate values for the key fields. A hashed secondary key does not have a predefined sorting order for the internal table, but uses a hash algorithm to store and access the table rows. For example, the following statement defines a hashed secondary key sec_key for an internal table itab that hashes the table by field1 and field2:

DATA itab TYPE STANDARD TABLE OF ty_itab WITH UNIQUE HASHED KEY sec_key COMPONENTS field1 field2.

You can then access the internal table using the hashed secondary key with a direct access algorithm, which is very fast.

• E. Secondary keys can only be created for standard tables. This is false because secondary keys can be created for any kind of internal table, such as standard tables, sorted tables, and hashed tables. However, the type of the secondary key depends on the type of the internal table. For example, a standard table can have sorted or hashed secondary keys, a sorted table can have sorted secondary keys, and a hashed table can have hashed secondary keys1.

References: 1: Secondary Table Key - ABAP Keyword Documentation 2: READ TABLE - ABAP Keyword Documentation 3: Sorted Tables - ABAP Keyword Documentation : Hashed Tables - ABAP Keyword Documentation

The patterns that raise an exception are those that use the constructor operator EXACT to perform a lossless assignment or calculation, but the result cannot be converted to the target data type without data loss. The following are the explanations for each pattern:

• A: This pattern raises the exception CX_SY_CONVERSION_LOST because the result of the calculation 2 * 3 is 6, which cannot be assigned to a packed number with two decimal places without losing the integer part. The operator -U is used to perform a lossless calculation with the calculation type decfloat34.
• B: This pattern does not raise an exception because the result of the substring expression gco_string+5(5) is ‘6789A’, which can be assigned to a string without data loss. The operator EXACT # is used to perform a lossless assignment with the data type of the argument.
• C: This pattern raises the exception CX_SY_CONVERSION_LOST because the result of the substring expression gco_string+5(6) is ‘6789AB’, which cannot be assigned to a character field with length 5 without losing the last character. The operator EXACT is used to perform a lossless assignment with the data type of the target field.
• D: This pattern does not raise an exception because the result of the calculation 2 / 2 is 1, which can be assigned to a packed number with three decimal places without data loss. The operator -U is used to perform a lossless calculation with the calculation type decfloat34.
• E: This pattern raises the exception CX_SY_CONVERSION_ERROR because the constant gco_date contains an invalid value ‘20331233’ for a date data type, which cannot be converted to a valid date. The operator EXACT is used to perform a lossless assignment with the data type of the target field.

References: EXACT - Lossless Operator - ABAP Keyword Documentation, Lossless Assignments - ABAP Keyword Documentation

The possible replacements for “???” in the CDS view entity definition with an input parameter are A. built-in ABAP type and C. A data element. These are the valid types that can be used to specify the data type of an input parameter in a CDS view entity. A built-in ABAP type is a predefined elementary type in the ABAP language, such as abap.char, abap.numc, abap.dec, etc. A data element is a reusable semantic element in the ABAP Dictionary that defines the technical attributes and the meaning of a field12. For example:

• The following code snippet defines a CDS view entity with an input parameter currency of type abap.cuky, which is a built-in ABAP type for currency key:

Define view entity Z_CONVERT With parameters currency : abap.cuky as select from … { … }

• The following code snippet defines a CDS view entity with an input parameter currency of type waers, which is a data element for currency key:

Define view entity Z_CONVERT With parameters currency : waers as select from … { … }

You cannot do any of the following:

• B. A built-in ABAP Dictionary type: This is not a valid type for an input parameter in a CDS view entity. A built-in ABAP Dictionary type is a predefined elementary type in the ABAP Dictionary, such as CHAR, NUMC, DEC, etc. However, these types cannot be used directly in a CDS view entity definition. Instead, they have to be prefixed with abap. to form a built-in ABAP type, as explained above12.
• D. A component of an ABAP Dictionary structure: This is not a valid type for an input parameter in a CDS view entity. A component of an ABAP Dictionary structure is a field that belongs to a structure type, which is a complex type that consists of multiple fields. However, an input parameter in a CDS view entity can only be typed with an elementary type, which is a simple type that has no internal structure12.

References: 1: ABAP CDS - SELECT, parameter_list - ABAP Keyword Documentation - SAP Online Help 2: ABAP Data Types - ABAP Keyword Documentation - SAP Online Help

ABAP SQL arithmetic expressions have different restrictions depending on the data type of the operands. The following are some of the restrictions:

• Floating point types and integer types can be used in the same expression, as long as the integer types are cast to floating point types using the cast function. For example, CAST ( num1 AS FLTP ) / CAST ( num2 AS FLTP ) is a valid expression, where num1 and num2 are integer types.
• The operator / is allowed only in floating point expressions, where both operands have the type FLTP or f. For example, num1 / num2 is a valid expression, where num1 and num2 are floating point types. If the operator / is used in an integer expression or a decimal expression, a syntax error occurs.
• Decimal types and integer types can be used in the same expression, as long as the expression is a decimal expression. A decimal expression has at least one operand with the type DEC, CURR, or QUAN or p with decimal places. For example, num1 + num2 is a valid expression, where num1 is a decimal type and num2 is an integer type.
• The operator ** is allowed only in floating point expressions, where both operands have the type FLTP or f. For example, num1 ** num2 is a valid expression, where num1 and num2 are floating point types. If the operator ** is used in an integer expression or a decimal expression, a syntax error occurs.

References: sql_exp - sql_arith - ABAP Keyword Documentation, SQL Expressions, Arithmetic Calculations - ABAP Keyword Documentation

You would use Access Controls with CDS Views for the following reasons:

• A. Only the data corresponding to the user’s authorization is transferred from the database to the application layer. This is true because Access Controls allow you to define CDS roles that specify the authorization conditions for accessing a CDS view. The CDS roles are evaluated for every user at runtime and the system automatically adds the restrictions to the selection conditions of the CDS view. This ensures that only the data that the user is authorized to see is read from the database and transferred to the application layer. This improves the security and the performance of the data access1.
• C. You do not have to remember to implement AUTHORITY CHECK statements. This is true because Access Controls provide a declarative and centralized way of defining the authorization logic for a CDS view. You do not have to write any procedural code or use the AUTHORITY CHECK statement to check the user’s authorization for each data source or field. The system handles the authorization check automatically and transparently for you2.

The following reasons are not valid for using Access Controls with CDS Views:

• B. The system field sy-subrc is set, giving you the result of the authorization check. This is false because the system field sy-subrc is not used by Access Controls. The sy-subrc field is used by the AUTHORITY CHECK statement to indicate the result of the authorization check, but Access Controls do not use this statement. Instead, Access Controls use CDS roles to filter the data according to the user’s authorization2.
• D. All of the data from the data sources is loaded into your application automatically and filtered there according to the user’s authorization. This is false because Access Controls do not load all the data from the data sources into the application layer. Access Controls filter the data at the database layer, where the data resides, and only transfer the data that the user is authorized to see to the application layer. This reduces the data transfer and the memory consumption of the application layer1.

References: 1: Access Controls | SAP Help Portal 2: ABAP CDS - Access Control - ABAP Keyword Documentation

In ABAP SQL, an alias is a temporary name that can be assigned to a field or a database table in a query. An alias can be used to make the query more readable, to avoid name conflicts, or to access fields or tables with long names. An alias is created with the AS keyword and is only valid for the duration of the query1.

The following are examples of how to assign an alias to a field or a database table in ABAP SQL:

• B. field (from field list): A field is a column of a table or a view that contains data of a certain type. A field can be assigned an alias in the field list of a SELECT statement, which specifies the fields that are selected from the data source. For example, the following query assigns the alias name to the field carrname of the table scarr:

SELECT carrid, carrname AS name FROM scarr.

The alias name can be used instead of carrname in other clauses of the query, such as WHERE, GROUP BY, ORDER BY, and so on2.

• C. database table: A database table is a collection of data that is organized in rows and columns. A database table can be assigned an alias in the FROM clause of a SELECT statement, which specifies the data source that is selected from. For example, the following query assigns the alias c to the table scarr:

SELECT c.carrid, c.carrname FROM scarr AS c.

The alias c can be used instead of scarr in other clauses of the query, such as WHERE, JOIN, GROUP BY, ORDER BY, and so on3.

The following are not valid for assigning an alias in ABAP SQL:

• A. order criterion (from order by clause): An order criterion is a field or an expression that is used to sort the result set of a query in ascending or descending order. An order criterion cannot be assigned an alias in the ORDER BY clause of a SELECT statement, because the alias is not visible in this clause. The alias can only be used in the clauses that follow the clause where it is defined1.
• D. group criterion (from group by clause): A group criterion is a field or an expression that is used to group the result set of a query into subsets that share the same values. A group criterion cannot be assigned an alias in the GROUP BY clause of a SELECT statement, because the alias is not visible in this clause. The alias can only be used in the clauses that follow the clause where it is defined1.

References: 1: ALIASES - ABAP Keyword Documentation 2: SELECT List - ABAP Keyword Documentation 3: FROM Clause - ABAP Keyword Documentation

• Use public SAP APIs and SAP extension points. This rule ensures that the ABAP Cloud code is stable, reliable, and compatible with the SAP solutions and the cloud operations. Public SAP APIs and SAP extension points are the only allowed interfaces and objects to access the SAP platform and the SAP applications. They are documented, tested, and supported by SAP. They also guarantee the lifecycle stability and the upgradeability of the ABAP Cloud code1.
• Build ABAP RESTful application programming model-based services. This rule ensures that the ABAP Cloud code follows the state-of-the-art development paradigm for building cloud-ready business services. The ABAP RESTful application programming model (RAP) is a framework that provides a consistent end-to-end programming model for creating, reading, updating, and deleting (CRUD) business data. RAP also supports draft handling, authorization checks, side effects, validations, and custom actions. RAP exposes the business services as OData services that can be consumed by SAP Fiori apps or other clients2.