1.创表语句

1.语法

MySQL 8.0之后，开始支持开窗函数； 语法格式：row_number() over(partition by 分组列 order by 排序列 desc) row_number() over()分组排序功能： 在使用 row_number() over()函数时候，over()里头的分组以及排序的执行晚于 where 、group by、 order by 的执行。

2.建表语句

create table TEST_ROW_NUMBER_OVER(
       id varchar(10) not null,
       name varchar(10) null,
       age varchar(10) null,
       salary int null
);

3.插入数据

insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(1,a,10,8000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(1,a2,11,6500);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(2,b,12,13000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(2,b2,13,4500);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,c,14,3000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,c2,15,20000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,d,16,30000);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(5,d2,17,1800);
insert into TEST_ROW_NUMBER_OVER(id,name,age,salary) values(3,d2,18,50000);

select * from TEST_ROW_NUMBER_OVER t;

2.row_number()over

需求1：查询基本信息，并新加一列，按照工资降序排列

select id,name,age,salary,row_number()over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t

需求2：查询基本信息，并新加一列，先以id分组再按照工资降序排列

方法一：

select id,name,age,salary,row_number()over(partition by id order by salary desc) rn from TEST_ROW_NUMBER_OVER t;

方法二：

select  * from (select id,name,age,salary,row_number() over(partition by id order by salary desc) rn from TEST_ROW_NUMBER_OVER) t1

需求3：查询基本信息，并新加一列，先以id分组再按照工资降序排列，并且排序数小于2

select  * from (select id,name,age,salary,row_number() over(partition by id order by salary desc) rn from TEST_ROW_NUMBER_OVER) t1
where t1.rn<2

需求4：查询基本信息，并新加一列，以工资降序排列，并且选出年龄再13到16之间的；

select id,name,age,salary,row_number()over(order by salary desc)  rn
from TEST_ROW_NUMBER_OVER t where t.age between 13 and 16

with 用法

with tabs as
(
    select id, name, age, salary, row_number()over(partition by id order by salary desc) rn
    from TEST_ROW_NUMBER_OVER t
)

在使用over等开窗函数时，over里头的分组及排序的执行晚于“where，group by，order by”的执行。

3.rank()over

需求1：查询基本信息，并新加一列，按照工资降序排列

select id,name,age,salary,rank()over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t

4.dense_rank()

需求1：查询基本信息，并新加一列，按照工资降序排列

select id,name,age,salary, DENSE_RANK() over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t

5.nitle()分组函数

需求1：查询基本信息，并新加一列分成4组，按照工资降序排列

select id,name,age,salary, NTILE(4)  over(order by salary desc) rn
from TEST_ROW_NUMBER_OVER t