PHP OR with MySQL和rowCount

Question

我想计算两个成员之间的对话次数。当用户1访问用户2的配置文件时，我会得到一个可见的结果。但是当用户2访问配置文件1时，我没有任何结果。

public function getNumberConversations($sender, $receiver) {

    $st = Database::getDatabase()->prepare("SELECT id, sender, receiver
        FROM conversation
        WHERE sender = ? AND receiver = ?
        OR receiver = ? AND sender = ?
    ");

    $st->execute(array($sender, $receiver, $receiver, $sender));

    return $st->rowCount();

  }

Answer 1

我认为你应该改变

$st->execute(array($sender, $receiver, $receiver, $sender));

使用

$st->execute(array($sender, $receiver, $sender, $receiver));

在您的情况下，括号是可以的(并且优先)

Answer 2

对条件使用大括号

public function getNumberConversations($sender, $receiver) {

    $st = Database::getDatabase()->prepare("SELECT id, sender, receiver
        FROM conversation
        WHERE (sender = ? AND receiver = ?)
        OR (receiver = ? AND sender = ?)
    ");

    $st->execute(array($sender, $receiver, $sender, $receiver)); // also notice this

    return $st->rowCount();

  }

Answer 3

对于分隔条件，您需要加上括号。此外，您在这两个上交换条件，因此它将变得相同。尝试以下答案：

public function getNumberConversations($sender, $receiver) {

    $st = Database::getDatabase()->prepare("SELECT id, sender, receiver
        FROM conversation
        WHERE (sender = ? AND receiver = ?)
        OR (receiver = ? AND sender = ?)
    ");

    $st->execute(array($sender, $receiver, $sender, $receiver)); //<----change here also

    return $st->rowCount();

  }