多次出现相同的值

Question

我正在尝试运行一个类似于下面的查询

"select * from 

(select datepart(wk,date)as week,count(*),platform 

from school 

where year(date) = 2015

group by datepart(wk,date)) a

full outer join

(select datepart(wk,date) as week,count(*),platform 

from school 

where year(date) = 2014

group by datepart(wk,date)) b

on b.week = a.week

order by b.week "

结果我多次得到相同的值。

谁能告诉我这是什么问题...

谢谢

Answer 1

您错过了群外的平台：

SELECT * 
FROM (
  SELECT DATEPART(wk,[date]) AS [week]
    ,COUNT(*)
    ,[platform] 
  FROM [school] 
  WHERE YEAR([date]) = 2015
  GROUP BY DATEPART(wk,[date]), [platform]
) [a]
FULL OUTER JOIN (
  SELECT DATEPART(wk,[date]) AS [week]
    ,COUNT(*)
    ,[platform] 
  FROM [school] 
  WHERE YEAR([date]) = 2014
  GROUP BY DATEPART(wk,[date]), [platform]
) [b]
ON [b].[week] = [a].[week]
ORDER BY [b].[week]

多次出现相同的值

Same value occuring multiple times

ssms