Question

所以这是一个类似于另一个的学校问题我得到了一个代码：

USE AP

SELECT VendorName, FirstInvoiceDate, InvoiceTotal
FROM Invoices JOIN
  (SELECT VendorID, MIN(InvoiceDate) AS FirstInvoiceDate
   FROM Invoices
   GROUP BY VendorID) AS FirstInvoice
  ON (Invoices.VendorID = FirstInvoice.VendorID AND
      Invoices.InvoiceDate = FirstInvoice.FirstInvoiceDate)
JOIN Vendors
  ON Invoices.VendorID = Vendors.VendorID
ORDER BY VendorName, FirstInvoiceDate

我需要更改此选项以创建视图而不是派生表我正在考虑更像

IF NOT EXISTS (SELECT * FROM sys.views
        Where name = ‘EarliestInvoiceandTotalVEW’)


CREATE View AS
Select VendorName, FirstInvoiceDate, InvoiceTotal
From Invoices JOIN
    (Create VIEW FirstInvoice AS
    SELECT VendorID, MIN(InvoiceDate) AS FirstInvoiceDate
    From Invoices
    Group By VendorID) As FirstInvoice
    ON (Invoices.VendorID = FirstInvoice.VendorID AND
      Invoices.InvoiceDate = FirstInvoice.FirstInvoiceDate)
JOIN Vendors
  ON Invoices.VendorID = Vendors.VendorID
ORDER BY VendorName, FirstInvoiceDate

这会使视图执行相同的操作并检查它是否存在，因此每次都不会重新创建/定义它。

感谢您的任何意见！

我为我直接从SQL Server中取出的格式道歉，它通常格式化得很好......

这就是我的工作：

 USE AP
 Declare @Create1 varchar(8000)

IF EXISTS (SELECT * FROM sys.views Where sys.views.name = 'EarliestInvoiceandTotalVIEW')
    drop view EarliestInvoiceandTotalVIEW;

SET @CREATE1 = 'CREATE View EarliestInvoiceTotalVIEW AS 
Select VendorName, FirstInvoiceDate, InvoiceTotal
From Invoices JOIN
  (SELECT VendorID, MIN(InvoiceDate) AS FirstInvoiceDate
   FROM Invoices
   GROUP BY VendorID) AS FirstInvoice
  ON (Invoices.VendorID = FirstInvoice.VendorID AND
      Invoices.InvoiceDate = FirstInvoice.FirstInvoiceDate)
JOIN Vendors
  ON Invoices.VendorID = Vendors.VendorID'

Exec (@CREATE1)

我必须设置sys.views.name = ...的位置，并设置一个exec命令，以便创建视图运行'first'。

Answer 1

在回复您的评论时，请务必使用GO语句围绕您的视图定义：

if exists (select * from sys.views where name = 'ThreeDigitsOfPi')
    drop view dbo.ThreeDigitsOfPi
GO
create view dbo.ThreeDigitsOfPi 
as
select  3.14 as PI
GO

其他一些观点：

您应该使用单引号'代替‘样式引号
您的观点必须有一个名称（create view NameOfView as ...）
view定义不能遵循if语句，除非视图是在动态SQL中创建的。例如：if not exists (...) exec('create view ...')

Answer 2

有多种方法可以检查视图是否存在。但是，通常的方法是删除视图（如果存在），然后重新创建它：

IF EXISTS (SELECT * FROM sys.views Where name = ‘EarliestInvoiceandTotalVEW’)
    drop view EarliestInvoiceandTotalVEW;

然后，您的create view声明有两个缺陷。首先，它缺少一个名字。其次，它内嵌了create view。您必须决定要创建哪一个 - 子查询的视图或整个语句的视图（我不清楚问题是正确的方法）。

SQL脚本创建视图而不是派生表

2 个答案: