Question

这是我要写的查询...

SELECT top 10 U.userid, U.fullname, U.username, T.tid, T.msg, T.tpic, T.ttime, COUNT(R.tid)
FROM USER_DETAILS AS U
INNER JOIN TWEET AS T ON U.userid = T.tuid
LEFT OUTER JOIN RETWEET AS R ON T.tuid = R.tid
WHERE (T.tuid IN (SELECT f.fuid FROM FOLLOW AS F WHERE F.userid = @usrid) OR T.tuid = @usrid)
ORDER BY T.ttime DESC;

我知道由于聚合而导致查询错误。我想要的只是被转发的推文的数量。那么更好的方法是什么呢？

表格是：

User_details(userid, fullname, username)

Follow(userid, fuid) where userid is following fuid

Tweet(tid, tuid)

Retweet(tid, ruid) where ruid is the user doing the retweet.

Answer 1

如果你解释你如何知道它是错的以及你知道它是什么问题，它会很有用，所以我可以确信你的所有问题都得到了解决。但是，显而易见的是，您没有group by子句，这是聚合工作所需要的。

SELECT top 10 U.userid, U.fullname, U.username, T.tid, T.msg, T.tpic, T.ttime, COUNT(R.tid)
FROM USER_DETAILS AS U
INNER JOIN TWEET AS T ON U.userid = T.tuid
LEFT OUTER JOIN RETWEET AS R ON T.tuid = R.tid
WHERE (T.tuid IN (SELECT f.fuid FROM FOLLOW AS F WHERE F.userid = @usrid) OR T.tuid = @usrid)
GROUP BY U.userid, U.fullname, U.username, T.tid, T.msg, T.tpic, T.ttime
ORDER BY T.ttime DESC;

获取以前连接的表中可能存在或不存在条目的列的值

1 个答案: