根据第二个查询中的时间对两个查询的结果进行排序[关闭]

Posted 2023-03-24

【中文标题】根据第二个查询中的时间对两个查询的结果进行排序[关闭]

【英文标题】：Order results from two queries based on time in second query [closed]

【发布时间】：2017-05-26 21:29:17

【问题描述】：

我需要按时间顺序获取结果，但是因为我在一段时间内使用 sql 查询进入另一个 sql 查询，所以我得到了由$arrID排序的结果

$req1==mysql_query("SELECT friendId FROM friends ");
while($res1=mysql_fetch_row($req1)) 
    $arrID = $res['friendId'];

    $req = mysql_query("SELECT * FROM posts WHERE postby=$arrID  ORDER BY posttime DESC ");
    while ($res = mysql_fetch_row($req)) 
        echo $res['bostby'];
        echo $res['postcontent'];
    

结果是：

post 1 by 2 content aaaaaaaa  time: 11:60
post 2 by 2 content bbbbbbbb   time 11:59
post 3 by 2 content aaaaaaaa  time: 11:58
post 4 by 2 content bbbbbbbb   time 11:56
post 5 by 3 content aaaaaaaa  time: 11:61
post 6 by 3 content bbbbbbbb   time 11:60
post 7 by 3 content aaaaaaaa  time: 11:59
post 8 by 5 content bbbbbbbb   time 12:20
post 8 by 5 content bbbbbbbb   time 12:19

我需要按时间而不是按 id 排序结果

post 8 by 5 content bbbbbbbb   time 12:20
post 8 by 5 content bbbbbbbb   time 12:19
post 1 by 2 content aaaaaaaa  time: 11:60
post 6 by 3 content bbbbbbbb   time 11:60
post 2 by 2 content bbbbbbbb   time 11:59
post 7 by 3 content aaaaaaaa  time: 11:59

【问题讨论】：

请stop using mysql_* functions。 These extensions 已在 php 7 中被删除。了解 PDO 和 @987654325 的 prepared 语句@ 并考虑使用 PDO，it's really pretty easy。

感谢的建议，但你能解决这个问题吗？？

并且不要在另一个查询中使用一个查询。请参阅 JOIN。

【参考方案1】：

使用连接两个表的单个查询，而不是执行嵌套循环。

SELECT p.* FROM posts AS p
JOIN friends AS f ON p.postby = f.friendId
ORDER BY p.posttime DESC

从您的评论看来，您的第一个查询并不那么简单。但是你可以加入一个子查询。

SELECT p.* FROM posts AS p
JOIN (
    SELECT user_from AS friendId
    FROM friend_requests 
    WHERE user_to = $SessionID AND accepted = '1'
    UNION
    SELECT user_to AS friendId
    FROM friend_requests
    WHERE user_from = $SessionID AND accepted = '1'
) AS f ON p.postby = f.friendId
ORDER BY p.posttime DESC

【讨论】：

_有点复杂，其实我用过这个reqq _$reqz="SELECT user_from FROM friend_requests WHERE ( user_to=".$SessionID." AND accepted='1' )UNION SELECT user_to FROM friend_requests WHERE (user_from=".$SessionID." AND accepted='1')"; $resz=mysql_query($reqz); while($rowz=mysql_fetch_row($resz)) $arrID = $rowz[0];

用JOIN (SELECT ... UNION SELECT ...)替换JOIN friends

**你能帮我修复孔代码吗？ :D **

刷新一下就可以看到了。

**OMG :o ** C:\wamp64\www\MY PROJECT\Hometest.php:18:boolean false