窗口函数：日期分组，销量降序，取每日排名前3

select   *   from 

(

select  * ,

row_number()  over(partition by 日期，order by 销量  desc ）px

from  table

) k

where k.px <=3

倒序取前七个不就可以了。

select top 7 from 表 where  日期 = getdate() - 30

SELECT 产品字段 ,count(产品字段)num  FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 30 DAY) <= date(时间字段名) GROUP BY 产品字段 ORDER BY num  limit 7  

--

不同的数据库top 7  的函数不一样

SELECT rq,num

from (SELECT rq,num,ROW_NUMBER() OVER(PARTITION BY rq ORDER BY num DESC) paixu

from(SELECT '0301' rq,1 num

union all

SELECT '0301',1

union all

SELECT '0302',3

union all

SELECT '0302',4

union all

SELECT '0303',1

union all

SELECT '0303',2

union all

SELECT '0304',3

union all

SELECT '0304',4)a)b

where paixu<2

SELECT 日期字段,GROUP_CONCAT(产品字段)  from(

select ROW_NUMBER() OVER(PARTITION BY 日期字段,产品字段 ORDER BY all_count desc) ID,日期字段,产品字段,count(产品字段) all_count  FROM 表名 

where 日期字段>=DATE_SUB(CURDATE(), INTERVAL 30 DAY)

 GROUP BY 日期字段,产品字段)A 

where ID<=3

group by 日期字段

数据库是：SqlServer？oracle？mysql？

SELECT * FROM (

SELECT  ROW_NUMBER() OVER(PARTITION BY 日期 ORDER BY 销量 DESC) [I],* FROM TABLE WHERE 日期>=DATEADD(DAY,-30,GETDATE()) ) T WHERE T.I<=3

SELECT

RQ,

WM_CONCAT ( ID ) 

FROM

(

SELECT

ROW_NUMBER ( ) OVER ( PARTITION BY TRUNC( DATE, 'DD' ) ORDER BY SUM( QTY ) DESC ) XH,

TRUNC( DATE, 'DD' ) RQ,

ID,

SUM( QTY ) SHUL 

FROM

MX 

WHERE

TRUNC( SYSDATE, 'DD' )-TRUNC( DATE, 'DD' ) <=30

GROUP BY

ID,

TRUNC( DATE, 'DD' ) 

ORDER BY

TRUNC( DATE, 'DD' ),

SUM( QTY ) DESC 

) 

WHERE

XH <= 3 

GROUP BY

RQ