从3个表查询中选择数据

Question

我的查询如下......

select * 
from UserMaster um 
inner join  ForumMaster fm on um.UserID = fm.UserID 
left join  
    (select * from CommentMaster cm) cmt on cmt.TopicID = @TopicID

我的表格如下......

• UserMaster（UserID, FName, LName）
• CommentMaster（CommentID, TopicID, Comment）
• ForumMaster（TopicID, UserID, Topic, DateCreated）

我希望上面三张表中的数据具有相同的TopicID ...

Answer 1

select * 
from UserMaster um 
    left outer join  ForumMaster fm on um.UserID = fm.UserID 
    left outer join  CommentMaster cm on cm.TopicId = fm.TopicId
where 
    cm.TopicId = @TopicId

Answer 2

试试这个

SELECT * FROM UserMaster um, CommentMaster cm, ForumMaster fm WHERE fm.UserID = um.UserID AND fm.TopicID = cm.TopicID

我在不使用join命令的情况下加入表。