How To Fix MC028 - Join using a constant in the foreign key

SAP Error Message - Details

• Message type: E = Error

• Message class: MC - Aggregate: views, matchcodes, lock objects

• Message number: 028

• Message text: Join using a constant in the foreign key

What causes this issue?

Two tables are linked to form a view using a foreign key relationship
containing a constant. This relationship has the same effect as if the
corresponding field of the check table is equated to the
constants in a selection condition. .

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?

Check whether you want this kind of an operation.

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message MC028 - Join using a constant in the foreign key ?

  The SAP error message MC028, which states "Join using a constant in the foreign key," typically occurs in the context of SAP BW (Business Warehouse) or when working with queries in SAP systems. This error indicates that there is an issue with how the join conditions are defined in a query or data model, specifically that a constant value is being used in a foreign key relationship.
  Cause:
  The error arises when a join condition in a query or data model is incorrectly defined to use a constant value instead of a variable or field reference. This can happen in various scenarios, such as:
  
  Incorrect Query Design: When designing a query, if a constant value is used in the join condition instead of a field from the data source.
  Data Model Issues: In the data model, if a foreign key relationship is defined using a constant rather than a dynamic reference to another table or field.
  Incompatible Data Types: If the data types of the fields being joined are incompatible, it may lead to this error.
  
  Solution:
  To resolve the MC028 error, you can take the following steps:
  
  
  Review the Query or Data Model:
  
  Check the join conditions in your query or data model. Ensure that you are using field references instead of constant values.
  If you find any constant values in the join conditions, replace them with appropriate field references.
  
  
  
  Adjust Data Types:
  
  Ensure that the data types of the fields being joined are compatible. If necessary, convert the data types to match.
  
  
  
  Test the Query:
  
  After making the necessary adjustments, test the query or data model to ensure that the error is resolved.
  
  
  
  Consult Documentation:
  
  If you are unsure about the correct join conditions or how to structure your query, refer to SAP documentation or seek guidance from SAP support or community forums.
  
  
  
  Related Information:
  
  SAP Notes: Check for any relevant SAP Notes that might address this specific error or provide additional context.
  SAP Community: Engage with the SAP Community forums where other users may have encountered similar issues and can provide insights or solutions.
  Training and Documentation: Consider reviewing training materials or documentation related to query design and data modeling in SAP BW or the specific SAP module you are working with.
  
  By following these steps, you should be able to identify and correct the issue causing the MC028 error in your SAP environment.