在服务器移动后，在非对象上调用成员函数prepare（）

Question

I am stumped, I changed hosts and I am now getting "Call to a member function prepare() on a non-object" on a script that has been working for months on the old server. I have read around here and tried several things I found but nothing seems to make it work again.

I am new at this so speak slowly and clearly please. ;)

$dbh = connect_db(); 

    $sql = 'SELECT count(*) FROM ppipn WHERE txn_id = :txn_id';
    $result = $dbh->prepare($sql); 
    $result->execute(array(':txn_id' => $txn_id)); 
    $number_of_rows = $result->fetchColumn(); 

    if ($number_of_rows>0){
    die();
    }

The function:

function connect_db()
{
    $DbHost = 'localhost';
    $DbName = '***n';
    $DbUser = '***';
    $DbPass = '***';
    $table;

    try
    {
        $connection = new PDO('mysql:host='.$DbHost.';dbname='.$DbName, $DbUser, $DbPass);
        $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $connection->setAttribute(PDO::ATTR_PERSISTENT, true);
    }
    catch (PDOException $e)
    {
        // Proccess error
        echo 'Cannot connect to database: ' . $e->getMessage();
    }

    return $connection;
}

Answer 1

This error means that $dbh in the line $dbh->prepare() is not an object.

Your connect_db() function can either return a built PDO object, or echo "Cannot connect" and return a variable named $connection, that is empty.

Your connect_db() function is almost certainly unable to connect, and you aren't seeing the error echo'd out.