MySQL aggregate function sorting

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'student number',
  `student_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT 'Student name',
  `sex` varchar(5) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT 'Gender\r\n',
  `age` int(11) NULL DEFAULT NULL COMMENT 'Age',
  `result` double(10, 0) NULL DEFAULT NULL COMMENT 'Results',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
INSERT INTO `student` VALUES (1, '小王', '男', 18, 90);
INSERT INTO `student` VALUES (2, 'Xiao Li', 'Female', 19, 80);
INSERT INTO `student` VALUES (3, 'Xiao Ming', 'Male', 20, 85);
INSERT INTO `student` VALUES (4, '小张', '男', 21, 87);

SELECT * FROM student ORDER BY age DESC ; 

select AVG(age) as "age" from student; 

select count(id) as "total number of people" from student; 

select age, count(id) as "total number of people" from student GROUP BY age; 

select MAX(age) as "Maximum age" from student; 

select sex ,count(*) AS "Number of people" from student GROUP BY sex;
#GROUP BY groups the results according to the following field names 

select sum(result) as "total score" FROM student;