以mysql为例，汇总sql查询最高分、最低分、平均分等sql语句，oracle语法类似，可自行修改以下sql语句
创建两个数据库表，一个学生表、一个考试成绩表
DROP TABLE IF EXISTS `score`;CREATE TABLE `score` ( `u_id` varchar(11) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '编号', `object_no` varchar(11) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '课程编号', `students_no` varchar(11) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '学号', `score` int(11) NULL DEFAULT NULL COMMENT '分数') ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;INSERT INTO `score` VALUES ('1', '100', 's100', 80);INSERT INTO `score` VALUES ('2', '100', 's200', 59);INSERT INTO `score` VALUES ('3', '100', 's300', 79);INSERT INTO `score` VALUES ('4', '200', 's100', 54);INSERT INTO `score` VALUES ('5', '200', 's200', 96);INSERT INTO `score` VALUES ('6', '200', 's300', 74);INSERT INTO `score` VALUES ('7', '300', 's100', 65);INSERT INTO `score` VALUES ('8', '300', 's200', 80);INSERT INTO `score` VALUES ('9', '200', 's400', 62);INSERT INTO `score` VALUES ('10', '300', 's400', 56);INSERT INTO `score` VALUES ('11', '100', 's400', 70);SET FOREIGN_KEY_CHECKS = 1;DROP TABLE IF EXISTS `students`;CREATE TABLE `students` ( `students_no` varchar(12) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '编号', `students_name` varchar(12) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '姓名', `sex` varchar(1) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '性别', PRIMARY KEY (`students_no`) USING BTREE) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;INSERT INTO `students` VALUES ('s100', '张三', '1');INSERT INTO `students` VALUES ('s200', '李四', '2');INSERT INTO `students` VALUES ('s300', '张三', '1');INSERT INTO `students` VALUES ('s400', '王五', '1');SET FOREIGN_KEY_CHECKS = 1;数据表数据
查询各课程的考试学生人数
select object_no as '课程编号', count(DISTINCT students_no) '考试人数' from score group by object_no
查询各科成绩最高分和最低分
select object_no as '课程编号',max(score) as '最高分',min(score) as '最低分' from score group by object_no
查询每门课程被选修的学生数
select object_no as '课程编号', count(DISTINCT students_no) as '学生编号' from score group by object_no
查询男生、女生人数
select sex '性别',count(DISTINCT students_no) '数量' from students group by sex
查询平均成绩
select students_no as '学生编号',avg(score) as '平均成绩' from score group by students_no
查询平均成绩大于70分学生的学号和平均成绩
select students_no as '学生编号',avg(score) as '平均成绩' from score group by students_no HAVING avg(score)>70
查询学生考试参与考试课程数量
select students_no as '学生编号',count(object_no) as '课程编号' from score group by students_no 
查询考试两门以上课程的学生学号
select students_no as '学生编号',count(object_no) as '课程编号' from score group by students_no HAVING count( object_no)>2
查询同名学生名单并统计同名人数
select students_name as '学生名称',count(students_name) as '同名数量' from students group by students_name HAVING count(students_name)>1
计算每门课程的平均成绩
select object_no as '课程编号',avg(score) as '平均成绩' from score group by object_no
计算每门课程的平均成绩并且平均成绩大于等于70分
select object_no as '课程编号',avg(score) as '平均成绩' from score group by object_no HAVING avg(score)>70
查询不及格的课程并按课程号从大到小排列
select object_no as '课程编号',students_no '学生编号',score '分数' from score where score<60 order by object_no desc
查询每门课程的平均成绩，结果按平均成绩降序排列，如果平均成绩相同时，按课程号升序排列
select object_no as '课程编号',avg(score) as '平均成绩' from score group by object_no order by avg(score) desc,object_no asc