SAP CDS PATH EXPR CARD V2

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• 1: ABAP_CDS_PATH_EXPR
• *: ABAP_CDS_PATH_EXPR
• EXACT ONE TO EXACT ONE ABAP_CDS_PATH_EXPR
• EXACT ONE TO ONE ABAP_CDS_PATH_EXPR
• EXACT ONE TO MANY ABAP_CDS_PATH_EXPR
• ONE TO EXACT ONE ABAP_CDS_PATH_EXPR
• ONE TO ONE ABAP_CDS_PATH_EXPR
• ONE TO MANY ABAP_CDS_PATH_EXPR
• MANY TO EXACT ONE ABAP_CDS_PATH_EXPR
• MANY TO ONE ABAP_CDS_PATH_EXPR
• MANY TO MANY ABAP_CDS_PATH_EXPR

ABAP_CDS_DDL - CDS View Entity, path_expr, cardinality

ABAP_SYNTAX_FORMS

Cardinality Syntax Written in Words
...$[ ${${EXACT ONE$} $| MANY $| ONE$} $] TO ${${EXACT ONE$} $|MANY $| ONE $}:


Numeric Syntax
... 1$|*: ...

What does it do?
Specifies the cardinality of the current CDS association as unique or non-unique. The cardinality can be specified in words or in numbers. The syntax written in words is recommended.
The syntax written in words can specify the source and target cardinalities. However, it is also possible to specify only the target cardinality. The source cardinality can be omitted. The following combinations are possible:

EXACT ONE TO EXACT ONE

EXACT ONE TO MANY

EXACT ONE TO ONE

MANY TO EXACT ONE

MANY TO MANY

MANY TO ONE

ONE TO EXACT ONE

ONE TO MANY

ONE TO ONE

TO ONE

TO EXACT ONE

TO MANY
The numeric syntax only specifies the target cardinality. The target cardinality can be specified either as 1 (to-one), or as * (to-many). The source cardinality is implicitly set to MANY .
A colon (:) must be placed at the end of the cardinality specification.
If the target cardinality is specified as to-one (using the syntax additions TO EXACT ONE:, TO ONE:, or 1:), it is possible to use filter conditions in path expressions, which are used in WHERE clauses or HAVING clauses. In a clause like this, it overwrites the cardinality of the CDS association.
The cardinality cannot be specified as the only addition in square brackets. It must always be combined with a filter condition.



Latest notes:
Specifying the cardinality as to-one cardinality prevents a syntax error if a path specified with filter conditions or with a non-unique cardinality is used in a WHERE clause or HAVING clause. However, at runtime, there is no check to validate whether the condition achieves the required unique cardinality.
NON_V5_HINTS
ABAP_HINT_END

ABAP_EXAMPLE_VX5
The following CDS view entity filters the association _Text using the cardinality specification written in words.
DDLS DEMO_CDS_PATH_EXP
The class CL_DEMO_CDS_PATH_EXPRESSION first enters data into the database tables using INSERT, and then selects data from the CDS view entity DEMO_CDS_PATH_EXP using a SELECT statement.
Due to the path expression with filter condition, the result set consists of three rows. Without filter condition, the result set would contain more rows.
ABAP_EXAMPLE_END