调用非对象上的成员函数rowCount() [英] Call to a member function rowCount() on a non-object

问题描述

我的查询有问题.我最近改用了PDO，这对我来说是新的.现在，我需要在查询中使用JOIN来从另一个表中获取数据，而无需执行两次执行.

Im having a problem with my query. I recently switched to PDO, which is kind of new to me. Now i need to use JOIN in my query to get data from another table without making two executions.

问题是，我收到此错误:

Problem is, i get this error:

Call to a member function rowCount() on a non-object

我不明白问题是什么.这是我的代码的样子:

I don't understand what the problem is. This is how my code looks like:

  $friends_string = "SELECT * FROM `friends` as F, `users` as U WHERE `F.userID` = '$sess_user' AND `F.request` = '0' AND `F.friendID` = 'U.id'";
  $friends = $db->query($friends_string);
  if ($friends->rowCount() > 0) {

while($row = $friends->fetch(PDO::FETCH_ASSOC)) {
    echo "<br /><a href='profile.php?id={$row["id"]}'>{$row["friendID"]}</a>";
  }

} else {
    echo "no Friends";
}

或者简而言之，只是查询:

Or for short, just the query:

SELECT * FROM `friends` as F, `users` as U WHERE `F.userID` = '$sess_user' AND `F.request` = '0' AND `F.friendID` = 'U.id'

我想要的是，从用户ID为session且请求为0的朋友那里获取所有行.但是然后我想获取用户中那些朋友的ID，以便我可以链接到他们的个人资料.请注意$row["id"]

What I want is, get all rows from friends where userID is session and request is 0. But then i want to get the ID of those friends in users so i can make a link to their profile. Note the $row["id"]

感谢您的反馈，不必回答我的问题，如果您发现任何问题，请发表评论.谢谢！

I appreciate any feedback, doesn't have to answer my questions, if you note any problem please comment it. Thanks!

推荐答案

不要在"table.field"周围打勾...您必须在"table..field"周围打勾.

Don't put back ticks around the `table.field` ... You have to put them around `table`.`field`

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