SQL 如何查找一個表里，每個班級各個學科的最高分？
學生表:STUDENT(S#,SNAME,SAGE,SSEX,CLASSNO)
班級表:CLASS(CLASSNO,CLASSNAME)
課程表:COURSE(C#,CNAME,T#)
成績表:SC(S#,C#,SCORE)
教師表:TEACHER(T#,TNAME)
SQL 創表腳本
-- 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 '學號';
comment on column STUDENT.sname
is '姓名';
comment on column STUDENT.sage
is '年齡';
comment on column STUDENT.ssex
is '性別';
comment on column STUDENT.classno
is '班級編號';
-- 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 '教師編號';
comment on column TEACHER.tname
is '教師姓名';
-- 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 '課程號';
comment on column COURSE.cname
is '課程名稱';
comment on column COURSE.t#
is '教師編號';
-- 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 '學號';
comment on column SC.c#
is '課程號';
comment on column SC.score
is '分數';
-- 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', '貂蟬', '18', '女', '2019001');
INSERT INTO STUDENT VALUES ('1003', '袁紹', '22', '男', '2019001');
INSERT INTO STUDENT VALUES ('1004', '劉備', '23', '男', '2019002');
INSERT INTO STUDENT VALUES ('1005', '小喬', '20', '女', '2019002');
INSERT INTO STUDENT VALUES ('1006', '關羽', '21', '男', '2019002');
INSERT INTO TEACHER VALUES ('801', '葉平');
INSERT INTO TEACHER VALUES ('802', '李華');
INSERT INTO TEACHER VALUES ('803', '劉明');
INSERT INTO TEACHER VALUES ('804', '李斯');
INSERT INTO COURSE VALUES ('1', '計算機組成原理', '801');
INSERT INTO COURSE VALUES ('2', '數據結構', '801');
INSERT INTO COURSE VALUES ('3', '數據庫原理及應用', '802');
INSERT INTO COURSE VALUES ('4', '計算機網絡', '802');
INSERT INTO COURSE VALUES ('5', '軟件工程', '803');
INSERT INTO COURSE VALUES ('6', 'C語言程序設計', '803');
INSERT INTO COURSE VALUES ('7', '人工智能', '804');
INSERT INTO COURSE VALUES ('8', '操作系統', '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');
</div>
```sql
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#
參考資料