在将其标记为重复问题之前先阅读。
有三个表-invoice_order、invoice_order_item和库存
这是的结构
发票订单
order_id | user_id | customer_name | order_date | order_number
1 | 1 | xyz | y-m-d | 0000001
invoice_order_item
这里order_id是外键，order_item_name存储stock_id
order_item_id | order_id | order_item_name | order_item_quantity | order_item_price
1 | 1 | 2 | 5 | 1000
库存
stock_id | item_type | item_name
2 | goods | Mobile
我正试着加入这三张桌子。这就是我迄今为止取得的成就
$query = "select * from invoice_order inner join invoice_order_item on invoice_order.order_id = invoice_order_item.order_id inner join stock on stock_id = invoice_order_item.order_item_name where invoice_order.order_id = {$order_id}";
上面的查询没有返回order_item_name。它输出stock_id而不是项名称。我需要输出商品的名称，而不是库存id。
我知道代码容易受到SQL注入的攻击。你可以忽略它，这只是为了测试
SELECT
Stock.item_name
FROM invoice_order
JOIN invoice_order_item
ON invoice_order.order_id = invoice_order_item.order_id
JOIN Stock
ON invoice_order_item.order_item_name = Stock.stock_id
参见参考