Question

我需要获取新闻的数量，它给了我错误

专栏＆＃39; News.NewsId＆＃39;在选择列表中无效，因为它不包含在聚合函数或GROUP BY子句中。

select    News.NewsId
        , News.NewsTitle
        , COUNT(News.NewsId) as Total 
from News inner join NewsCategory on News.NewsId = NewsCategory.NewsId
where NewsCategory.CategoryId in (Select CategoryId 
                                  from Category 
                                  where CategoryName = 'travel' 
                                    or  CategoryName = 'Technology' 
                                    or  CategoryName = 'Sport')

Answer 1

您需要按列NewsId和NewsTitle

进行分组

select    News.NewsId
        , News.NewsTitle
        , COUNT(News.NewsId) as Total 
from News inner join NewsCategory on News.NewsId = NewsCategory.NewsId
where NewsCategory.CategoryId in 
                        (Select CategoryId 
                         from Category 
                         where CategoryName IN ('travel','Technology','Sport'))
GROUP BY News.NewsId
        , News.NewsTitle

或者您可以将查询编写为

select    News.NewsId
        , News.NewsTitle
        , COUNT(News.NewsId) as Total 
from News 
inner join NewsCategory on News.NewsId = NewsCategory.NewsId
inner join Category     on Category.CategoryId = NewsCategory.CategoryId
where Category.CategoryName IN ('travel','Technology','Sport'))
GROUP BY News.NewsId, News.NewsTitle

Answer 2

像这样使用ti：

select    News.NewsId, News.NewsTitle, COUNT(News.NewsId) as Total from News  group by  News.NewsId, News.NewsTitle
inner join 
NewsCategory
on News.NewsId = NewsCategory.NewsId where NewsCategory.CategoryId in (Select CategoryId from Category where CategoryName = 'travel' or  CategoryName = 'Technology' or CategoryName = 'Sport')'Technology' or CategoryName = 'Sport')

您正在使用计数，这就是您需要按字段分组的原因，包括在您的计数中（News.NewsId）

根据每个NewsId显示每个类别的计数：

select count(1), a.NewsId, a.NewsTitle,b.category from
(select  NewsId, NewsTitle from tbl_news)as a


left JOIN

(select    NewsId, categoryid,Category  from tbl_category) as b
on a.newsid = b.newsid GROUP BY a.NewsTitle,b.category

Answer 3

只需使用两个连接和一个group by：

来编写

select n.NewsId, n.NewsTitle, COUNT(*) as Total 
from News n inner join
     NewsCategory nc
     on n.NewsId = nc.NewsId join
     Category c
     on nc.CategoryId = c.CategoryId
where c.CategoryName in ('travel', 'Technology', 'Sport')
group by n.NewsId, n.NewsTitle;

SQL Server选择加入计数

3 个答案: