php - 如何在 mysqli 准备语句中使用多个内部连接和多个 WHERE 子句？

Question

这个问题在这里已经有了答案:





Fatal error: Call to a member function bind_param() on boolean [duplicate]

(12 个回答)



mysqli_fetch_array(): Argument #1 must be of type mysqli_result. How to deal with mysqli problems?

(1 个回答)


5年前关闭。




我正在尝试编写一个查询，我想使用基于第一个连接条件的 WHERE 子句和基于第二个连接的第二个 WHERE 子句进行选择。我已经写了几种方法，但它总是显示一个错误:

Fatal error: Call to a member function bind_param() on boolean in /var/www/html/connections.php on line 80

$user_id 正在从其他地方获取。所以没有问题，如果我在这里运行一个单一的连接，它工作正常。

这是我的查询:

方法一:

$sql = $db->prepare("SELECT r.* from registered_users r 
        inner join connections c2 on r.id = c2.uid
        inner join connections c on r.id = c.connections_userid where c2.connections_userid = ? or c.uid = ?");

$sql->bind_param("ii",$user_id,$user_id);           
$sql->execute();

方法二:

$sql = $db->prepare("SELECT r.* from registered_users r 
        inner join connections c2 on r.id = c2.uid where     c2.connections_userid = ?
        inner join connections c on r.id = c.connections_userid where c.uid = ?");

$sql->bind_param("ii",$user_id,$user_id);           
$sql->execute();

Answer 1

你的准备有错误，所以检查一下

$sql = $db->prepare("SELECT r.* from registered_users r 
    inner join connections c2 on r.id = c2.uid
    inner join connections c on r.id = c.connections_userid where c2.connections_userid = ? or c.uid = ?");

if (!$sql) {
   //error !! Let's report it!
   trigger_error($db->error);
}

$sql->bind_param("ii",$user_id,$user_id);           
$sql->execute();