No key field found for creation of DataSource - Classification Datasource

Question

Hello,
While trying to create a clasiffication datasource based on 0PLANT_ATTR, when i assign a characteristic and push the DataSource button, i get the following message:
No key field found for creation of DataSource
Diagnosis
During generation of a classification or configuration DataSource, only those key fields for the object table (field "Obj.Tabelle") that are already present in the basis DataSource transferred to the extract structure.  This is the case when none of the key fields of the object table were found in the structure of the basis DataSource.
System response
A DataSource cannot be created without key fields. The action was cancelled.
Procedure
Check whether you have selected the correct basis DataSource and object table. For more information, please see SAP Note 569849.
Do you know what can be the problem?
Thank you and regards

Answer 1

Hi Alberto,
plants are a special case. The key which is used for the classification 
of plants (object type BETR) is not the same as the key which is used in
datasource 0PLANT_ATTR.
BETR has key LOCNR (Site). That's a customer related to a plant. The    
customer number will be extracted in field LOCNR.
0PLANT_ATTR extracts the plant in its key field WERKS.
Transaction CTBW and the generic extraction program for classifications 
don't know the relationship between LOCNR and WERKS. So they cannot map     
them.
I do recommend a solution which would add the mapping between
LOCNR and WERKS:
1. Create please the classification datasource as intended, but use     
datasource 0RT_LOC_MGR_ATTR as basis datasource. It's the only          
datasource of the content where LOCNR is a key field. So                
0RT_LOC_MGR_ATTR is used as a dummy here, to allow transaction CTBW to  
create the classification datasource. It's not necessary to extract     
data with datasource 0RT_LOC_MGR_ATTR.
2. Extend please the extract structure of the created classification    
datasource. Add please field WERKS using component type WERKS_D. Make   
this field visible.
3. Fill field WERKS in the extractor user exit EXIT_SAPLRSAP_002. WERKS 
can be read from table KNA1 by using the customer number extracted to   
LOCNR to select on field KNA1-KUNNR.
4. Transaction CTBW_META on the BW system isn't able to append the      
characteristics from the classification datasource to infosource        
0PLANT, because the keys are different. So create please a new info     
source with CTBW_META. This allows CTBW_META to create the info objects 
for the characteristics used in the classification datasource.
5. Add please the characteristics used in the classification datasource 
to infosource 0PLANT manually. You will find the info object names of   
the characteristics by looking up the characteristic datasources which  
are assigned to the classification datasource in transaction CTBW. From 
these names you can derive the info object names:                       
1CL_A... -> C_A...
6. Disconnect the infosource which has been created with CTBW_META from 
the classification datasource.
7. Connect please the classification datasource to infosource 0PLANT    
Use following info object:
info object   field
0PLANT       WERKS
The info object names for the characteristics are explained in step 5.
8. Add an infopackage to infosource 0PLANT for the classification       
datasource.
Now the extraction of classifications of sites should work.
Best regards,
Rolf
P.S. I saw the system messed it up and doesn't display any new and empty lines. Sorry, I hope you still can read it.
Edited by: Rolf Doersam on Mar 26, 2010 6:56 PM