>>>>Do you want to see the date and hour and minute when that max rating was achieved? This would make more sense but the query will be a bit more complex.
>>>>
>>>>I would go with the composed column solution for this case, e.g.
>>>>

>>>>select max(mRating) as MaxRating,
>>>>RIGHT(max(cast(mRating as C(20)) + CAST(mIndex as C(14))),14) as WhenMaxRatingHappened,
>>>>LEFT(CAST(mIndex as C(14)),6) AS YearMonth
>>>>FROM Tab1
>>>>GROUP BY 3

>>>
>>>Thank you for the above! The FULL JOIN produces this output:
>>>
>>>

>>>SumMax's  YYMM
>>>20.5             201301
>>>19.2             201302
>>>

>>>
>>>For a report, it would really help to have the option of including the MAX ratings for each table, such as:
>>>
>>>

>>>MaxT1  Max T2  SumMax's  YYMM
>>>5.6       4.1     9.7      201301
>>>2.4       1.3     3.7      201302
>>>

>>>
>>>And here it is:
>>>
>>>

>>>select  ;
>>>t1.RatingMax	as t1MAX,;
>>>t2.RatingMax	as t2MAX,;
>>>NVL(T1.RatingMax,0) + NVL(T2.RatingMAX,0) as SumMAXs, ;
>>>NVL(T1.yyMMddhh, T2.yyMMddhh)  AS yyMMddhh	;
>>>FROM;
>>>T1	 ;
>>>FULL JOIN  ;
>>>T2	;
>>>ON T1.yymmddhh = T2.yymmddhh
>>>

>>
>>Yes, this is correct.
>
>

>select max(mRating) as MaxRating;
>RIGHT(max(cast(mRating as C(20)) ;   && contains unrecognized key word ??
>+;
>CAST(mIndex as C(14))),14) ;
>as ;
>WhenMaxRatingHappened;
>LEFT(CAST(mIndex as C(14)),6) AS YearMonth;
>FROM Tab1;
>GROUP BY 3
>

You're now missing a comma after MaxRating.

BTW, why do you need this column anyway? I thought you didn't need it for your report.