>>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.