While implementing the Cognos 10 Audit package on an Oracle 10g system, I ran into a problem with one of the pre-defined reports.  This one report would fail each time, reporting an Oracle error:  ORA-12704 character set mismatch.

My first Google search indicated that there was a problem with Cognos 8.3 Audit package on Oracle 10g.  A modification was required in the Framework Manager model, changing all references from nVarChar to characterLength16.  Although I was running Cognos 10, I decided to try this fix out.  It did not adversely affect my Audit package, but it did not resolve the issue either.  As all the model query subjects were working as expected in the original Framework Manager model, I reverted back to it and decided to focus my efforts on the Report Studio report.

Eventaully I isolated the problem down to three If/Then/Else statements in the report, and then realized it was not able to compare query results against an empty string.  I casted this empty string into a nvarchar and the problem was resolved:

IF [Audit].[Audit Report Table].[Audit Report Column] = ” THEN…

became

IF [Audit].[Audit Report Table].[Audit Report Column] = cast(”, nvarchar(1)) THEN…