OVER(PARTITION_BY)函数介绍.

--学生表

create table st1(id number primary key,st_name varchar2(10));

--课程表

create table course1(id number primary key,course_name varchar2(8));

--成绩表

create table score(id number primary key,st_id number,course_id number,score number,foreign key

(st_id) references st1(id),foreign key(course_id) references course1(id));

--

insert into st1 values(1,'aom');

insert into st1 values(2,'bom');

insert into st1 values(3,'com');

insert into st1 values(4,'dom');

insert into st1 values(5,'eom');

insert into st1 values(6,'fom');

insert into st1 values(7,'fom');

--

insert into course1 values(1,'语文');

insert into course1 values(2,'数学');

insert into course1 values(3,'英语');

--

insert into score values(1,1,1,100);

insert into score values(2,1,2,99);

insert into score values(3,1,3,98);

insert into score values(4,2,1,97);

insert into score values(5,2,2,96);

insert into score values(6,2,3,95);

insert into score values(7,3,1,94);

insert into score values(8,3,2,93);

insert into score values(9,3,3,92);

insert into score values(10,4,1,91);

insert into score values(11,4,2,90);

insert into score values(12,4,3,89);

insert into score values(13,5,1,88);

insert into score values(14,5,2,87);

insert into score values(15,5,3,86);

insert into score values(16,6,1,85);

insert into score values(17,6,2,84);

insert into score values(18,6,3,83);

insert into score values(19,7,1,100);

insert into score values(20,7,2,99);

insert into score values(21,7,3,77);

--1.选出每门成绩排名前三名学生的姓名、课程名、分数(并列时名次会一样，后面的排名会跳过排如1,1,3)

select * from

(select a4.* ,rank()over(partition by a4.course_name order by a4.score desc) a5 from

(select a1.st_name,a2.course_name,a3.score from st1 a1,course1 a2,score a3

where a1.id=a3.st_id and a2.id=a3.course_id

) a4

)

where a5<=3;

--或（并列时按顺序排如1,2,3）

select * from

(select a4.* ,row_number()over(partition by a4.course_name order by a4.score desc) a5 from

(select a1.st_name,a2.course_name,a3.score from st1 a1,course1 a2,score a3

where a1.id=a3.st_id and a2.id=a3.course_id

) a4

)

where a5<=3;