Php 按日期时间组织MySQL结果

使用PHP，我试图找到一种方法来组合多个MySQL查询的结果，并将它们放入一个按日期时间戳排序的数组中，该数组在数据库中保存在“timestamp”下

我的代码：

        $reactions = DB::query('SELECT * FROM reactions WHERE poster_id=:userid', array(':userid' => $userid));
        $comments = DB::query('SELECT * FROM comments WHERE poster_id=:userid', array(':userid' => $userid));
        $mentions = DB::query('SELECT * FROM comments WHERE FIND_IN_SET(:users , users)', array(':users' => $userid));
        $postMentions = DB::query('SELECT * FROM posts WHERE FIND_IN_SET(:users , users)', array(':users' => $userid));

编辑： 更新代码

$reactions = "'SELECT timestamp as date FROM reactions WHERE poster_id=:userid', array(':userid' => $userid)";
        $comments = "'SELECT timestamp as date FROM comments WHERE poster_id=:userid', array(':userid' => $userid)";
        $mentions = "'SELECT timestamp as date FROM comments WHERE FIND_IN_SET(:users , users)', array(':users' => $userid)";
        $postMentions = "'SELECT timestamp as date FROM posts WHERE FIND_IN_SET(:users , users)', array(':users' => $userid)";

        $sql = 'SELECT timestamp FROM ('.$reactions.' UNION ALL '.$comments.' UNION ALL '.$mentions.' UNION ALL '.$postMentions.') as combined order by timestamp desc';

        $result = DB::query($sql, array());

        print_r($result);

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你们可以通过联合来实现同样的目标。请尝试下面的代码片段

$reactions = 'SELECT reactions.date as date FROM reactions WHERE poster_id=:userid', array(':userid' => $userid);
$comments = 'SELECT comments.date as date FROM comments WHERE poster_id=:userid', array(':userid' => $userid);
$mentions = 'SELECT comments.date as date FROM comments WHERE FIND_IN_SET(:users , users)', array(':users' => $userid);
$postMentions = 'SELECT posts.date as date FROM posts WHERE FIND_IN_SET(:users , users)', array(':users' => $userid);

$sql = SELECT combined.date from (".$reactions." UNION ALL ".$comments." UNION ALL ".$mentions." UNION ALL ".$postMentions.") as combined order by combined.date desc;

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你在mysql中尝试过“联合”吗？@KimberleeHo-no，我从来没有听说过。我该如何在代码中实现这一点？我正在使用DB类中的查询。另外，我不使用combined.date或其中任何一个，它们是必需的吗？添加这一行

$result=DB:：query（$sql）这应该执行您的查询…这里的组合是一个表别名。我尝试实现它，但它给了页面一个“HTTP错误500”，我将更新的代码编辑到了主问题中。