Question

我有2张桌子

客户

customerid    
customername

订单

customerid
orderid
isopen [true/false]

如何创建包含以下内容的视图：

客户名称，总订单，总订单，其中isopen column == true

的的 *更新**

create view CustomerOrders as
select c.id CustomerID, 
       max(c.customername) CustomerName,
       count(o.order_id) CustomerOrders,
       SUM(CASE WHEN o.isopen = 1 THEN 1 ELSE 0 END) AS OpenOrders
from customer c
left join orders o on c.id = o.customerid
group by c.id

谢谢大家请更正你的答案，以便我能给你留下标记

Answer 1

尝试：

CREATE VIEW v1 AS 
  SELECT customername, count(orderid) as total_orders 
   FROM customer c
   LEFT JOIN orders o ON ( c.id = o.customerid AND o.isopen = TRUE)
  GROUP BY c.id

Answer 2

尝试下面给出的语法

 Create View OpenOrders AS
       SELECT CUSTOMERNAME, count(ORDERID) FROM CUSTOMER INNER JOIN ORDERS
                CUSTOMER.CUSTOMERID = ORDERS.CUSTOMERID
       WHERE ORDERS.ISOPEN =1;

Answer 3

尝试：

create view CustomerOrders as
select c.customerid CustomerID, 
       max(c.customername) CustomerName,
       count(o.order_id) CustomerOrders,
       SUM(CASE WHEN o.isopen = 1 THEN 1 ELSE 0 END) OpenOrders
from customer c
left join orders o on c.customerid = o.customerid
group by c.id

（假设您希望包含没有订单的客户 - 如果您只想包含订单的客户，请将左连接更改为内部联接。）

Answer 4

你不能这样做，直到你有customerid属性和customername。他们不会联系其他

Answer 5

这将是这样的，取决于表定义的细节（你没有提到）：

create view viewname as
 select c.customername, count(o.*) as totalorders
  from customer c, orders o
   where c.customerid = o.customerid and o.isopen

如何写这个视图

5 个答案: