SQL数据查询错误：关键字“ join”附近的语法不正确

Question

我正在尝试开发一个查询： https://data.stackexchange.com/stackoverflow/query/new

也许你们可以帮忙：

1. 鉴于用户当前的热门标签，我想找到类似的问题，
2. 具有最高的观看次数（即大于500），但也有
3. 少于20个答案。
4. 按观看次数排序

第二段中的某个地方，这里的联接查询附近有错误发生：join #tags t on t.TagId = TagId，说：关键字'join'附近的语法不正确。

非常感谢您的帮助：

        DECLARE @UserId int = ##UserId##

        create table #tags (TagId int, [Count] int)
        insert #tags 
        SELECT TOP 20 
        TagId,
        COUNT(*) AS UpVotes 
        FROM Tags
          INNER JOIN PostTags ON PostTags.TagId = Tags.id
          INNER JOIN Posts ON Posts.ParentId = PostTags.PostId
          INNER JOIN Votes ON Votes.PostId = Posts.Id and VoteTypeId = 2
        WHERE 
          Posts.OwnerUserId = @UserId
        GROUP BY TagId
        ORDER BY UpVotes DESC  

        select top 2000 [Post Link], Views
        join #tags t on t.TagId = TagId  
        where
          ViewCount > 500 and AnswerCount < 20
        order by ViewCount desc 

更新

DECLARE @UserId int = ##UserId##

    create table #tags (TagId int, [Count] int)
    insert #tags 
    SELECT TOP 20 
    TagId,
    COUNT(*) AS UpVotes 
    FROM Tags
      INNER JOIN PostTags ON PostTags.TagId = Tags.id
      INNER JOIN Posts ON Posts.ParentId = PostTags.PostId
      INNER JOIN Votes ON Votes.PostId = Posts.Id and VoteTypeId = 2
    WHERE 
      Posts.OwnerUserId = @UserId
    GROUP BY TagId
    ORDER BY UpVotes DESC  

    select top 2000 [Post Link], Views
    from Posts
    join #tags t on t.TagId = posts.TagId  
    where
      posts.ViewCount > 500 and posts.AnswerCount < 20
      order by posts.ViewCount desc 

，但是Posts表具有标签列：nvarchar（250）。我该如何匹配？

Answer 1

我认为您在加入之前错过了“ FROM”语句

Answer 2

表变量是批处理范围变量（t1是另一个临时表中的变量，仅以temp中的t1为例）。

select top 2000 [Post Link], Views
        join #tags t, #tags t1 on t.TagId = t1.TagId  
        where
          t.ViewCount > 500 and t.AnswerCount < 20
        order by t.ViewCount desc