SQLSTATE [42000]：使用LEFT OUTER JOIN时出现语法错误或访问冲突

Question

我试图使用PDO执行查询，但它会引发错误。

  

SQLSTATE [42000]：语法错误或访问冲突：1064您有   SQL语法错误;查看与您的手册相对应的手册   MariaDB服务器版本，用于在＆＃39;＆＃39;附近使用正确的语法在第3行

$db = PrestaDB::getInstance($shop->getHost(), $shop->getLogin(), $shop->getPassword(), $shop->getDbName());

$statement = '
    SELECT *
    FROM ps_orders o
    JOIN ps_customer c ON c.id_customer = o.id_customer
    JOIN ps_carrier car ON car.id_carrier = o.id_carrier
    JOIN ps_address a ON o.id_address_delivery = a.id_address
    JOIN ps_address ai ON o.id_address_invoice = ai.id_address
    LEFT OUTER JOIN ps_customer_thread ct ON ct.id_order = o.id_order
    LEFT OUTER JOIN ps_customer_message cm ON cm.id_customer_thread = ct.id_customer_thread
    ORDER BY o.date_add DESC
';

if ($result = $db->query($statement)) {
    while ($row = $result->fetch(\PDO::FETCH_OBJ)) {
        print_r($row);
    }
}

当我删除

LEFT OUTER JOIN ps_customer_thread ct ON ct.id_order = o.id_order
LEFT OUTER JOIN ps_customer_message cm ON cm.id_customer_thread = ct.id_customer_thread

从查询它工作正常。该查询有什么问题？