Question

在此网站http://www.w3schools.com/sql/sql_view.asp上，它表示我可以按如下方式更新视图：

CREATE VIEW [Current Product List] AS
SELECT ProductID,ProductName,Category
FROM Products
WHERE Discontinued=No

但是，我创建了如下所示的视图：

CREATE VIEW ProductCustomers AS    
SELECT cust_name, cust_contact, prod_id     
FROM Customers, Orders, OrderItems      
WHERE Customers.cust_id = Orders.cust_id
AND Orders.order_num = OrderItems.order_num

然后尝试通过建议的语法更新它：

CREATE VIEW ProductCustomers AS    
SELECT cust_name, cust_contact, prod_id,cust_address --JUST ADDING THE COLUMN cust_address
FROM Customers, Orders, OrderItems      
WHERE Customers.cust_id = Orders.cust_id
AND Orders.order_num = OrderItems.order_num

我得到错误：“数据库中已经有一个名为'ProductCustomers'的对象。数据库中已经有一个名为'ProductCustomers'的对象。”所以我不确定如何在我的视图中添加新列。

由于

Answer 1

您需要使用ALTER VIEW

ALTER VIEW ProductCustomers AS

Answer 2

DROP VIEW ProductCustomers
GO
CREATE VIEW ProductCustomers AS   
SELECT cust_name, cust_contact, prod_id,cust_address     FROM Customers, Orders, OrderItems     
WHERE Customers.cust_id = Orders.cust_id
AND Orders.order_num = OrderItems.order_num
Go

Answer 3

这是我在定义对象时使用的一种实用方法（在本例中是一个视图）。

if object_id('[dbo].[viewName]') is not null --object already exists
   set noexec on;
go
create view [dbo].[viewName] as
   select 'not implemented' as message
go
set noexec off;
go
alter view [dbo][viewName] as
--your actual view definition here

作为解释，此代码检查视图是否已存在。如果它不存在，则创建存根。一旦执行或跳过存根创建部分，就会保证存在该名称的视图，因此保证alter view语句可以正常工作。

语法混淆更新视图

3 个答案: