SQL Get Other Rows From Aggregate Function

Question

I have an aggregate function that does a group by (col A). It selects the maximum value from a set of columns(col B), but I also want to return another value from a column

Answer 1

since you haven't mention the RDBMS you are using, use this query which works on almost all RDBMS

SELECT  a.*
FROM    tableName a
        INNER JOIN
        (
            SELECT  A, MAX(b) max_B
            FROM    tableName
            WHERE   b > 50
            GROUP   BY A
        ) b ON a.A = b.A   AND
            a.B = b.max_B

• SQLFiddle Demo

But if your RDBMS support window functions, you can use DENSE_RANK()

SELECT  A, B, C
FROM    
        (
            SELECT  A, B, C,
                    DENSE_RANK() OVER (PARTITION A ORDER BY B DESC) rn
            FROM    tableName
            WHERE   b > 50
            GROUP   BY      
        ) a
WHERE   rn = 1