mysql> CREATE TABLE tbl(a INT, b INT, t VARCHAR(255));
Query OK, 0 rows affected (0.14 sec)

mysql> INSERT INTO tbl (a,b) VALUES(1,3),(1,4),(1,8),(2,2),(2,5),(3,2),(4,4),(4,7);
Query OK, 8 rows affected (0.01 sec)
Records: 8  Duplicates: 0  Warnings: 0

mysql> UPDATE tbl SET t=CONCAT('(', a, ',', b, ')');
Query OK, 8 rows affected (0.00 sec)
Rows matched: 8  Changed: 8  Warnings: 0

mysql> SELECT a, MAX(b), t FROM tbl GROUP BY a;
+------+--------+-------+
| a    | MAX(b) | t     |
+------+--------+-------+
|    1 |      8 | (1,3) |
|    2 |      5 | (2,2) |
|    3 |      2 | (3,2) |
|    4 |      7 | (4,4) |
+------+--------+-------+
4 rows in set (0.00 sec)

mysql> SELECT a, MAX(b), t FROM tbl GROUP BY a ORDER BY b DESC;
+------+--------+-------+
| a    | MAX(b) | t     |
+------+--------+-------+
|    4 |      7 | (4,4) |
|    1 |      8 | (1,3) |
|    2 |      5 | (2,2) |
|    3 |      2 | (3,2) |
+------+--------+-------+
4 rows in set (0.00 sec)

mysql>