KB245815: ORA-00979 error occurs when case statement is used in Group-by while Oracle native driver does not throw the error.

SYMPTOM:
  In Strategy 9.4.x, an ORA-00979 error occurs when a case statement is used in the Group-by, while the Oracle native driver does not throw the error as shown in the image below:

Error: SQL Generation Complete

QueryEngine encountered error: Execute Query failed.

Error type: Odbc error. Odbc operation attempted: SQLExecDirect. [HY000:979: on SQLHANDLE] [Strategy][ODBC Oracle Wire Protocol driver][Oracle]ORA-00979: not a GROUP BY expression 
Connection String: DSN=mstr2;UID=MSTR2;HOST=localhost;PORT=1521;SID=XE;. SQL Statement: 
selectcase when a11.SEGMENT_CD is null or a11.SEGMENT_CD = '' then n' ' else a11.SEGMENT_CD end  CustCol_1,
sum(a11.COST)  WJXBFS1
from F58AW080 a11
where a11.STATUS_CD = '2'
group by case when a11.SEGMENT_CD is null or a11.SEGMENT_CD = '' then n' ' else a11.SEGMENT_CD end..

Error in Process method of Component: QueryEngineServer, Project NewProject, Job 1149, Error Code= -2147212544.

1. Create a database table with 3 columns, SEGMENT_CD, STATUS_CD and COST.
2. Create an attribute with the following expression: ApplySimple("case when #0 is null or #0 = '' then n' ' else #0 end", [SEGMENT_CD])
3. Create an attribute which is mapped to the STATUS_CD column.
4. Create a fact mapped to the COST column.
5. Create a metric based off the fact created in the previous step, Sum(cost).
6. Create a report and add the attribute from Step 2 and the metric from Step 5.
7. Add the filter which qualifies the attribute from Step_3 on ‘STATUS_CD (ID) Exactly 2’.
8. Run the report and note that an ORA-00979 error occurs.
9. No error is thrown when running the same SQL through the Oracle Native driver.

 
ACTION:
The error is not thrown by setting the hidden connect option TreatEmptyAsNull to "0".
Add TreatEmptyAsNull=0 in the field for "Extended Options" under the Advance tab of DSN as shown in the image below: