SQL从三个关联表中选择数据

Question

我有三张桌子：

*orders:

  -id (PK)

  -iduser (FK)

  -date



*detail_orders:

  -id(PK)

  -or_id (FK of id on orders)

  -prod_id (FK of id on products)

  -price

  -quantity


*products:

  -id (PK)

  -description

有订单的表格，订单的另一个明细（产品，价格，数量）和另一个要检索描述的产品

我想从特定的iduser（从php检索）使用mysql来获取它：

order.id | order.date:

products.description | orders.quantity | orders.price
products.description | orders.quantity | orders.price
products.description | orders.quantity | orders.price

... (etc while there are products on this order)

查询应该如何？我有经验只从一个sql表中检索数据，并且没有来自多个数据库的连接数据。

Answer 1

您需要JOIN表格，如下所示：

SELECT products.description, orders.quantity, orders.price
FROM detail_orders
  INNER JOIN products ON (products.prod_id = detail_orders.prod_id)
  INNER JOIN orders ON (orders.id = detail_orders.or_id)

如果您想查询特定用户：

    SELECT products.description, orders.quantity, orders.price
    FROM detail_orders
      INNER JOIN products ON (products.prod_id = detail_orders.prod_id)
      INNER JOIN orders ON (orders.id = detail_orders.or_id)
    WHERE orders.iduser = someUser