目录
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