使用LEFT OUTER JOIN在单个查询中连接多个表

Question

我在多个表格中使用LEFT OUTER JOIN时遇到了困难。

我的表格为：countries，customer_info，package_types，service_types和shipping_info

到目前为止，这是我的代码：

$sql = "SELECT shipping_info.shipping_id, shipping_info.weight, shipping_info.width, shipping_info.height, shipping_info.length, shipping_info.cost, shipping_info.status, 
service_types.service, package_types.package_type, countries1.country AS fromCountry, countries2.country AS toCountry, countries3.country AS resiCountry, customer_info.name, customer_info.address
, customer_info.city, customer_info.postcode, customer_info.zipcode, customer_info.phone, customer_info.email, customer_info.country
FROM shipping_info 
LEFT OUTER JOIN service_types ON shipping_info.service_type = service_types.serviceType_id 
LEFT OUTER JOIN package_types ON shipping_info.package_type = package_types.packageType_id 
LEFT OUTER JOIN customer_info ON shipping_info.customer_id = customer_info.customer_id
LEFT OUTER JOIN countries AS countries1 ON shipping_info.from_loc = countries1.country_id 
LEFT OUTER JOIN countries AS countries2 ON shipping_info.to_loc= countries2.country_id 
LEFT OUTER JOIN countries AS countries3 ON shipping_info.to_id = countries3.country_id";

$statement = $con_db->query($sql);
$result = $statement->fetchAll();

我在最后一行中遇到了致命错误，我相信这是因为$ result为null。但是我无法弄清楚错误。

感谢任何帮助。

Answer 1

可能是您的查询有以下手动错误：

tablename 或 fieldname 不匹配