Help how to write a SQL statement

Abstract: Help how to write a SQL statement

Abc
1 ww 100
2 ww 110
3 mm 90
4 mm 95
5 mm 120
6 yy 480
7 yy 70
8 tt 300
9 tt 150

Above is a form of a SQL statement, I hope that this has the following effects

Abc
6 yy 480
8 tt 300
5 mm 120
2 ww 110

B field is not repeated. . . . . Thank you very simple sort C field

SELECT distinct (b) FROM table t order by tc;

Select * from table group by b order by c desc

Select * from table group by b order by c desc
The same as a floor, I do not authorized personal opinions

Not above the maximum, OK
Select * from (select a, b, max (c) as c from tab group by b) as t order by c desc;

Above this ok

Oh, too late!

Select max (a), b, max (c) from table group by b order by c desc

Select * from (select a, b, max (c) as c from tab group by b) as t order by c desc;
The OK

Thank you, but I am not solve my problem b field investigations are linked to the table, I do not test for the N line, the group by a single table on it. .

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