How To Fix E2180 - Constant foreign key selected (select only one alternative)

SAP Error Message - Details

• Message type: E = Error

• Message class: E2 - DE Data Dictionary

• Message number: 180

• Message text: Constant foreign key selected (select only one alternative)

What causes this issue?

You created a foreign key field and also marked the foreign key as a
constant foreign key with an entry in column <LS>Constant</>.
With constant foreign keys, a constant is assigned to a table field.
Only this constant is checked.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Remove the entries for the foreign key field in columns <ZH><ZK>For.key
table</></> and <ZH><ZK>Foreign key field</></> or cancel the entry for
the constant.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message E2180 - Constant foreign key selected (select only one alternative) ?

  The SAP error message E2180, "Constant foreign key selected (select only one alternative)," typically occurs in the context of database operations, particularly when dealing with foreign key relationships in ABAP programs or when defining database views. This error indicates that the system has detected a situation where a constant foreign key is being used, which is not allowed in certain contexts.
  Cause:
  The error is usually caused by one of the following scenarios:
  
  Multiple Foreign Key Alternatives: When defining a foreign key relationship, if multiple alternatives are provided, the system expects only one to be selected. If the definition includes constants or multiple options, it leads to this error.
  Incorrect Data Model: The data model may have been incorrectly defined, leading to ambiguity in foreign key relationships.
  Improper Use of Constants: Using constants in a way that conflicts with the expected foreign key behavior can trigger this error.
  
  Solution:
  To resolve the E2180 error, consider the following steps:
  
  
  Review Foreign Key Definitions: Check the foreign key definitions in your database table or view. Ensure that only one alternative is selected and that it does not include constants that could lead to ambiguity.
  
  
  Modify the ABAP Code: If the error arises from ABAP code, review the relevant SELECT statements or data retrieval logic. Ensure that you are not trying to select multiple foreign key alternatives simultaneously.
  
  
  Check Data Model: If you are working with a data model, ensure that the relationships are correctly defined and that there are no conflicting definitions.
  
  
  Use Dynamic Selection: If applicable, consider using dynamic selection methods to handle foreign keys more flexibly, ensuring that only one alternative is selected at a time.
  
  
  Consult Documentation: Refer to SAP documentation or help resources for specific guidelines on defining foreign keys and handling related errors.
  
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any specific patches or updates related to this error.
  ABAP Documentation: Review the ABAP documentation for best practices on handling foreign keys and database operations.
  Community Forums: Engage with SAP community forums or support channels for insights from other users who may have encountered and resolved similar issues.
  
  By following these steps, you should be able to identify the root cause of the E2180 error and implement an appropriate solution.