How To Fix AQQIS_CNTRL021 - &1 cannot be connected to two tables using left-outer join

SAP Error Message - Details

• Message type: E = Error

• Message class: AQQIS_CNTRL - Join-Control InfoSet

• Message number: 021

• Message text: &1 cannot be connected to two tables using left-outer join

What causes this issue?

The system tried to insert a join or convert a join into a left-outer
join.
The definition would lead to a join condition that does not support
ABAP-SQL at the moment:
The right-hand table would be connected with more than one table across
a left-outer join.
This is not allowed.

System Response

The change was undone.

How to fix this error?

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

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.

Smart SAP Assistant

• What is the cause and solution for SAP error message AQQIS_CNTRL021 - &1 cannot be connected to two tables using left-outer join ?

  The SAP error message AQQIS_CNTRL021 indicates that there is an issue with a query that attempts to connect two tables using a left outer join, but the system is unable to do so due to certain constraints or configurations. This error typically arises in the context of SAP BW (Business Warehouse) or SAP HANA when working with queries or data models.
  Cause:
  
  
  Incompatible Join Conditions: The tables you are trying to join may not have compatible join conditions. For a left outer join to work, there must be a valid relationship defined between the two tables.
  
  
  Data Model Configuration: The data model may not be set up correctly. For example, if the tables are not part of the same InfoProvider or if the join conditions are not properly defined in the data model.
  
  
  Cardinality Issues: The cardinality of the relationship between the two tables may not support a left outer join. For instance, if one table has unique values and the other has multiple entries for the same key, it may lead to issues.
  
  
  Query Design: The query itself may have been designed in a way that does not allow for a left outer join due to the way the fields are selected or aggregated.
  
  
  Solution:
  
  
  Check Join Conditions: Review the join conditions between the two tables. Ensure that the fields used for the join are correctly defined and that they have compatible data types.
  
  
  Review Data Model: Ensure that both tables are part of the same InfoProvider or data model. If they are in different InfoProviders, consider creating a new InfoProvider that includes both tables.
  
  
  Adjust Cardinality: If the cardinality is causing issues, consider adjusting the data model to ensure that the relationship between the tables supports a left outer join.
  
  
  Modify Query Design: If the query design is causing the issue, try modifying the query to ensure that it adheres to the requirements for a left outer join. This may involve changing the fields selected or how they are aggregated.
  
  
  Consult Documentation: Refer to SAP documentation or help resources for specific guidelines on how to set up joins in your version of SAP BW or HANA.
  
  
  Related Information:
  
  SAP Notes: Check SAP Notes for any known issues or patches related to this error message.
  SAP Community: Engage with the SAP Community forums to see if other users have encountered similar issues and what solutions they have found.
  Training and Documentation: Consider reviewing training materials or documentation related to data modeling and query design in SAP BW or HANA to better understand how to set up joins correctly.
  
  By following these steps, you should be able to identify the cause of the error and implement a solution to resolve it.