PHP ORDER BY 不工作嵌套查询

Question

因此，我一直在尝试为实践项目创建一个用户事件页面，在页面上显示他们的所有事件及其 friend 的事件。我已经完成了这个工作，但由于查询是嵌套的，无法按日期排序。问题是我必须首先获取用户的 friend ，它位于一个表中，然后我必须获取提及该用户的通知。

进行查询的最佳方式是什么，以便可以按日期排序。感谢您的帮助!

表格的设置大致如下:

一个用户

ID ||名字 ||姓氏 ||用户名

B friend

用户 ID ||好友ID

C 墙贴:

Wallpost_id ||来自用户 ID || to_user_id ||墙柱||约会时间 代码如下:

 try {
$DBH = new PDO("mysql:host=$host;dbname=$db_name", $username, $password);


$DBH->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );

} catch(PDOexception $e) {
echo $e->getMessage();
}

try {
$myid = $_SESSION['identification'];


$result = $DBH->prepare("SELECT Friends.*, users.id, users.Firstname,users.Lastname FROM Friends
        JOIN users ON Friends.Friends=users.id

     WHERE Friends.id=:myid");
$result->execute(array(':myid' => $myid));
$result->setFetchMode(PDO::FETCH_ASSOC);
$r = $result->fetchAll();

echo "<br><br><br>";
echo "<ul>";



try{
$stmt = $DBH->prepare("CREATE TEMPORARY TABLE usering(`user_id` int(10) , `First_Name` varchar(250), `Last_Name` varchar(250), `user_name` varchar(135), `password` varchar(135), `NaCl` varchar(135))");
$stmt->execute();

$stmy = $DBH->prepare("INSERT INTO usering(`user_id`, `First_Name`, `Last_Name`, `user_name`, `password`, `NaCl`) SELECT * from users");
$stmy->execute();
}catch(PDOexception $e) {
echo $e->getMessage();
}


try {

foreach($r as $row){

$FriendId = $row['Friends'];

$result2 = $DBH->prepare("SELECT wallpost.*, usering.*, users.* FROM wallpost
JOIN usering ON wallpost.from_user_id=usering.user_id
JOIN users ON wallpost.to_user_id=users.id
 WHERE :FriendId in (from_user_id, to_user_id) ORDER BY wallpost_id DESC
                        ");

$result2->execute(array(':FriendId' => $FriendId));
$result2->setFetchMode(PDO::FETCH_ASSOC);

$r2 = $result2->fetchAll();
    foreach($r2 as $row2){
    $from_user_id = $row2['from_user_id'];
    $fromUsername = $row2['user_name'];
    $from_user_name = $row2['First_Name'] . " " . $row2['Last_Name'];
    $to_user_name = $row2['Firstname'] . " " . $row2['Lastname'];
    $toUsername = $row2['username'];
    $to_user_id = $row2['to_user_id'];
    $wallpost = $row2['wallpost'];

    /*"<div class='miniprofile_right'><img class='microphoto' src='../" . $from_username . "/profile.jpg'><div class='status_text'><a href='../" . $from_username . "/" . $from_user_id . "profile.php'>" . $from_user_firstname . " " . $from_user_lastname . "</a> => ". $firstname . " " . $lastname . ":</br>" . $walldate2 . "<br>" . $wallpost . " - at " . $walltime .  "</div></div><br><br>"*/
    if($from_user_id == $to_user_id){
    echo "<div class='miniprofile_right'><img class='microphoto' src='../members/" . $fromUsername . "/profile.jpg'><div class='status_text'><a href='../members/" . $fromUsername . "/" . $from_user_id . "profile.php'>" . $from_user_name . "</a> posted a status: <br>" . $wallpost . "</div></div></br></br>";
    } else {
    echo "<div class='miniprofile_right'><img class='microphoto' src='../members/" . $fromUsername . "/profile.jpg'><div class='status_text'><a href='../members/" . $fromUsername . "/" . $from_user_id . "profile.php'>" . $from_user_name . "</a> posted on " . "<a href='../members/" . $toUsername . "/" . $to_user_id . "profile.php'>" . $to_user_name . "'s" . "</a> wall: <br> " . $wallpost . "</div></div></br></br>";
    }
    }
    }
}catch(PDOexception $e) {
echo $e->getMessage();
}

echo "</ul>";




} catch(PDOexception $e) {
echo $e->getMessage();
}

Answer 1

尝试创建一个类/对象并将条目输入其中。运行所有查询并且相关数据位于您的新类中后，排序应该很简单。

因此，只要您的查询检索到正确的信息，如果查询太长，您就可以在 SQL 之外对数据进行排序