我如何优化这个动态SQL查询？

Question

我一直遇到以下问题。我一直在试图优化它，或许使它更具可读性。假设我有3个表orders_returned，orders_completed，orders_delivered与匹配列oder_id，customer_id。根据选定的选项，我可能需要检索已交付的订单，然后返回并最终完成（具有相同customer_id的所有三个表中相同的order_id）。此外，我可能只需要检索只发货和退货的订单，在这种情况下，我将省略AND order_id IN (SELECT order_id FROM ORDERS_COMPLETED)从WHERE条款。例如，获取传递和返回客户约翰和蒂姆· 订单截至目前我的查询看起来是这样的：

SELECT order_id 
FROM 
(
    SELECT order_id, customer_id 
    FROM ORDERS_RETURNED 
    UNION 
    SELECT order_id, customer_id 
    FROM ORDERS_COMPLETED 
    UNION 
    SELECT order_id, customer_id 
    FROM ORDERS_DELIVERED 
) 
WHERE 
    customer_id IN ('customer1', 'customer2', ...) 
    AND order_id IN (SELECT order_id FROM ORDERS_RETURNED) 
    AND order_id IN (SELECT order_id FROM ORDERS_COMPLETED) 
    AND order_id IN (SELECT order_id FROM ORDERS_DELIVERED) 

我还在学习SQL，想看看有没有更好的选择。

编辑：我正在使用Oracle数据库。还有订单表有不同的order_ids和一些其他不相关的列。它不存储customer_ids。 此外，订单可能发生在一张表中或两张中，所以我认为这些连接在这里没有用处。

Answer 1

您应该使用连接而不是内部/嵌套查询。

下面尝试，而不是::

SELECT A.order_id, A.customer_id FROM ORDERS_RETURNED A 
INNER JOIN ORDERS_COMPLETED B ON A.order_id = B.order_id AND A.customer_id = B.customer_id 
INNER JOIN ORDERS_DELIVERED C ON A.order_id = C.order_id AND A.customer_id = C.customer_id 
Where A.customer_id IN ('customer1', 'customer2', ...) 

Answer 2

既然你有一个订单表，我想你也存储在客户在该表也是如此。假设如此，试试这个：

SELECT DISTINCT O.OrderId 
FROM Orders O 
    LEFT JOIN Orders_Completed OC ON O.OrderId = OC.OrderId 
    LEFT JOIN Orders_Delivered OD ON O.OrderId = OD.OrderId 
    LEFT JOIN Orders_Returned ORE ON O.OrderId = ORE.OrderId 
WHERE O.CustomerId IN (...) 
    AND OD.OrderId IS NOT NULL AND ORE.OrderId IS NOT NULL AND OC.OrderId IS NULL 

此特定的查询将返回所有不同的订单，其中客户在（...），其中订单已交付和返回，但尚未完成。切换使用IS NULL和IS NOT NULL来获得所需的输出。

祝你好运。从数据

with data 
    as (select customer_id, 
       order_id, 
       nvl(max(case status when 'RETURNED' then 'Y' end), 'N') returned, 
       nvl(max(case status when 'COMPLETED' then 'Y' end), 'N') completed, 
       nvl(max(case status when 'DELIVERED' then 'Y' end), 'N') delivered 
      from (select 'RETURNED' status, order_id, customer_id 
        from orders_returned 
       union all 
       select 'COMPLETED' status, order_id, customer_id 
        from orders_completed 
       union all 
       select 'DELIVERED' status, order_id, customer_id 
        from orders_delivered) 
      group by customer_id, order_id) 
select * 
    from data 
where returned = 'Y' 
    and delivered = 'Y' 
    and customer_id in ('xx', 'xxx') ; 

或

with data 
    as (select customer_id, 
       order_id, 
       max(returned) returned, 
       max(completed) completed, 
       max(delivered) delivered 
      from (select 'Y' returned, null completed, null delivered, order_id, customer_id 
        from orders_returned 
       union all 
       select null, 'Y', null, order_id, customer_id 
        from orders_completed 
       union all 
       select null, null, 'Y', order_id, customer_id 
        from orders_delivered) 
      group by customer_id, order_id) 
select * 

其中返回= 'Y' 和（'XX交付= 'Y' 和CUSTOMER_ID：

Answer 3

你可能喜欢的东西做到这一点'，'xxx'）;

例如：http://sqlfiddle.com/#!4/3e2fb/2