Oracle中row_number() over partition by 转换mysql
Oracle中row_number() over partition by 转换mysql
row_number() over (partition by col1 order by col2)表示根据col1分组，在分组内部根据col2排序，而此函数计算的值就表示每组内部排序后的顺序编号（组内连续的唯一的）
Oracle中的用法
-- 新建一个表
CREATE TABLE td_school
(
name VARCHAR2(30), -- 姓名
age int, -- 年龄
class VARCHAR2(30), -- 班级
subject VARCHAR2(30), -- 学科
achievement int -- 成绩
)
-- 插入数据
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','语文',80);
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','数学',60);
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','英语',100);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','语文',90);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','数学',80);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','英语',70);
insert into td_school (name,age,class,subject,achievement) values ('小王',21,'002','语文',100);
insert into td_school (name,age,class,subject,achievement) values ('小王',21,'002','数学',90);
insert into td_school (name,age,class,subject,achievement) values ('小黄',18,'002','语文',30);
insert into td_school (name,age,class,subject,achievement) values ('小张',18,'002','语文',70);
-- 按照姓名分组并已成绩由低到高排序
SELECT t.*,row_number() over (partition by t.name order by t.achievement) rn from td_school t
最终的查询结果
mysql中的用法
-- 新建一个表
create table `td_school`
(
`name` varchar(30), -- 姓名
`age` int, -- 年龄
`class` varchar(30), -- 班级
`subject` varchar(30), -- 学科
`achievement` int -- 成绩
)
-- 插入数据
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','语文',80);
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','数学',60);
insert into td_school (name,age,class,subject,achievement) values ('小明',18,'001','英语',100);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','语文',90);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','数学',80);
insert into td_school (name,age,class,subject,achievement) values ('小红',20,'001','英语',70);
insert into td_school (name,age,class,subject,achievement) values ('小王',21,'002','语文',100);
insert into td_school (name,age,class,subject,achievement) values ('小王',21,'002','数学',90);
insert into td_school (name,age,class,subject,achievement) values ('小黄',18,'002','语文',30);
insert into td_school (name,age,class,subject,achievement) values ('小张',18,'002','语文',70);
-- 按照姓名分组并已成绩由低到高排序
select
r.name,r.age,r.class,r.subject,r.achievement,rn
from
(
select
t.*,@rownum := @rownum + 1,
if (
@pdept = t.name, -- 定义一个变量，给变量赋值需要分组的字段
@rank := @rank + 1 ,@rank := 1 -- 每次循环到这个字段rank就加1
) as rn,
@pdept := t.name
from
(
select * from td_school order by name,achievement
) t,
(
select @rownum := 0, @grade := null ,@pdept := null ,@rank := 0
) a
) r;
-- 如果需要多项分组可使用concat连接
select
r.name,r.age,r.class,r.subject,r.achievement,rn
from
(
select
t.*,@rownum := @rownum + 1,
if (
@pdept = concat(t.name,t.class),
@rank := @rank + 1 ,@rank := 1
) as rn,
@pdept := concat(t.name,t.class)
from
(
select * from td_school order by name,class,achievement
) t,
(
select @rownum := 0, @grade := null ,@pdept := null ,@rank := 0
) a
) r;
最终的查询结果
