SQL 如何查找一个表里，每个班级各个学科的最高分？

SQL 如何查找一个表里，每个班级各个学科的最高分？

学生表:STUDENT(S#,SNAME,SAGE,SSEX,CLASSNO)

班级表:CLASS(CLASSNO,CLASSNAME)

课程表:COURSE(C#,CNAME,T#)

成绩表:SC(S#,C#,SCORE)

教师表:TEACHER(T#,TNAME)

SQL 创表脚本

-- Create table
create table CLASS
(
  classno   INTEGER not null,
  classname NVARCHAR2(32)
);
-- Add comments to the columns 
comment on column CLASS.classno
  is '班级编号';
comment on column CLASS.classname
  is '班级名称';
-- Create/Recreate primary, unique and foreign key constraints 
alter table CLASS
  add constraint PK_CLASS primary key (CLASSNO);


-- Create table
create table STUDENT
(
  s#      INTEGER not null,
  sname   NVARCHAR2(32),
  sage    INTEGER,
  ssex    NVARCHAR2(8),
  classno INTEGER
);
-- Add comments to the columns 
comment on column STUDENT.s#
  is '学号';
comment on column STUDENT.sname
  is '姓名';
comment on column STUDENT.sage
  is '年龄';
comment on column STUDENT.ssex
  is '性别';
comment on column STUDENT.classno
  is '班级编号';
-- Create/Recreate primary, unique and foreign key constraints 
alter table STUDENT
  add constraint PK_STUDENT primary key (S#);
alter table STUDENT
  add constraint FK_STUDENT_CLASS foreign key (CLASSNO)
  references CLASS (CLASSNO);


-- Create table
create table TEACHER
(
  t#    INTEGER not null,
  tname NVARCHAR2(16)
);
-- Add comments to the columns 
comment on column TEACHER.t#
  is '教师编号';
comment on column TEACHER.tname
  is '教师姓名';
-- Create/Recreate primary, unique and foreign key constraints 
alter table TEACHER
  add constraint PK_TEACHER primary key (T#);


-- Create table
create table COURSE
(
  c#    INTEGER not null,
  cname NVARCHAR2(32),
  t#    INTEGER
);
-- Add comments to the columns 
comment on column COURSE.c#
  is '课程号';
comment on column COURSE.cname
  is '课程名称';
comment on column COURSE.t#
  is '教师编号';
-- Create/Recreate primary, unique and foreign key constraints 
alter table COURSE
  add constraint PK_COURSE primary key (C#);
alter table COURSE
  add constraint FK_COURSE_TEACHER foreign key (T#)
  references TEACHER (T#);


-- Create table
create table SC
(
  s#    INTEGER,
  c#    INTEGER,
  score INTEGER
);
-- Add comments to the columns 
comment on column SC.s#
  is '学号';
comment on column SC.c#
  is '课程号';
comment on column SC.score
  is '分数';
-- Create/Recreate primary, unique and foreign key constraints 
alter table SC
  add constraint FK_SC_COURSE foreign key (C#)
  references COURSE (C#);
alter table SC
  add constraint FK_SC_STUDENT foreign key (S#)
  references STUDENT (S#);


INSERT INTO CLASS VALUES ('2019001', '火箭一班');
INSERT INTO CLASS VALUES ('2019002', '火箭二班');

INSERT INTO STUDENT VALUES ('1001', '曹操', '21', '男', '2019001');
INSERT INTO STUDENT VALUES ('1002', '貂蝉', '18', '女', '2019001');
INSERT INTO STUDENT VALUES ('1003', '袁绍', '22', '男', '2019001');
INSERT INTO STUDENT VALUES ('1004', '刘备', '23', '男', '2019002');
INSERT INTO STUDENT VALUES ('1005', '小乔', '20', '女', '2019002');
INSERT INTO STUDENT VALUES ('1006', '关羽', '21', '男', '2019002');

INSERT INTO TEACHER VALUES ('801', '叶平');
INSERT INTO TEACHER VALUES ('802', '李华');
INSERT INTO TEACHER VALUES ('803', '刘明');
INSERT INTO TEACHER VALUES ('804', '李斯');

INSERT INTO COURSE VALUES ('1', '计算机组成原理', '801');
INSERT INTO COURSE VALUES ('2', '数据结构', '801');
INSERT INTO COURSE VALUES ('3', '数据库原理及应用', '802');
INSERT INTO COURSE VALUES ('4', '计算机网络', '802');
INSERT INTO COURSE VALUES ('5', '软件工程', '803');
INSERT INTO COURSE VALUES ('6', 'C语言程序设计', '803');
INSERT INTO COURSE VALUES ('7', '人工智能', '804');
INSERT INTO COURSE VALUES ('8', '操作系统', '804');

INSERT INTO SC VALUES ('1001', '1', '61');
INSERT INTO SC VALUES ('1001', '2', '67');
INSERT INTO SC VALUES ('1001', '3', '91');
INSERT INTO SC VALUES ('1001', '4', '66');
INSERT INTO SC VALUES ('1001', '5', '95');
INSERT INTO SC VALUES ('1001', '6', '68');
INSERT INTO SC VALUES ('1001', '7', '73');
INSERT INTO SC VALUES ('1001', '8', '99');
INSERT INTO SC VALUES ('1002', '1', '94');
INSERT INTO SC VALUES ('1002', '2', '85');
INSERT INTO SC VALUES ('1002', '3', '69');
INSERT INTO SC VALUES ('1002', '4', '78');
INSERT INTO SC VALUES ('1002', '5', '70');
INSERT INTO SC VALUES ('1002', '6', '77');
INSERT INTO SC VALUES ('1002', '7', '83');
INSERT INTO SC VALUES ('1002', '8', '81');
INSERT INTO SC VALUES ('1003', '1', '77');
INSERT INTO SC VALUES ('1003', '2', '70');
INSERT INTO SC VALUES ('1003', '3', '97');
INSERT INTO SC VALUES ('1003', '4', '92');
INSERT INTO SC VALUES ('1003', '5', '65');
INSERT INTO SC VALUES ('1003', '6', '89');
INSERT INTO SC VALUES ('1003', '7', '79');
INSERT INTO SC VALUES ('1003', '8', '66');
INSERT INTO SC VALUES ('1004', '1', '70');
INSERT INTO SC VALUES ('1004', '2', '95');
INSERT INTO SC VALUES ('1004', '3', '78');
INSERT INTO SC VALUES ('1004', '4', '68');
INSERT INTO SC VALUES ('1004', '5', '72');
INSERT INTO SC VALUES ('1004', '6', '98');
INSERT INTO SC VALUES ('1004', '7', '81');
INSERT INTO SC VALUES ('1004', '8', '84');
INSERT INTO SC VALUES ('1005', '1', '93');
INSERT INTO SC VALUES ('1005', '2', '96');
INSERT INTO SC VALUES ('1005', '3', '73');
INSERT INTO SC VALUES ('1005', '4', '76');
INSERT INTO SC VALUES ('1005', '5', '85');
INSERT INTO SC VALUES ('1005', '6', '90');
INSERT INTO SC VALUES ('1005', '7', '77');
INSERT INTO SC VALUES ('1005', '8', '62');
INSERT INTO SC VALUES ('1006', '1', '84');
INSERT INTO SC VALUES ('1006', '2', '86');
INSERT INTO SC VALUES ('1006', '3', '63');
INSERT INTO SC VALUES ('1006', '4', '66');
INSERT INTO SC VALUES ('1006', '5', '60');
INSERT INTO SC VALUES ('1006', '6', '87');
INSERT INTO SC VALUES ('1006', '7', '65');
INSERT INTO SC VALUES ('1006', '8', '99');

SELECT  s.classno,
        c.cname,
        max(sc.score)
FROM student s
LEFT JOIN sc
    ON s.s# = sc.s#
LEFT JOIN course c
    ON sc.c# = c.c#
GROUP BY  s.classno,c.cname
ORDER BY  s.classno;

SELECT  s.classno,
        c.cname,
        sc.score
FROM student s
LEFT JOIN sc
    ON s.s# = sc.s#
LEFT JOIN course c
    ON sc.c# = c.c#
ORDER BY  c.cname,sc.score desc,s.s#

参考资料

• http://www.w3school.com.cn/sql/sql_join.asp