帮助创建计算列（sql server 2008）

Question

问候。

需要与此表上创建一个计算列一些帮助：

USE [ScienceWorksSummary] 

GO 

/****** Object: Table [dbo].[Authors_Articles] Script Date: 04/07/2011 10:38:55 ******/ 
SET ANSI_NULLS ON 
GO 

SET QUOTED_IDENTIFIER ON 
GO 

CREATE TABLE [dbo].[Authors_Articles](
    [IdAuthor] [int] NOT NULL, 
    [IdArticle] [int] NOT NULL, 
    [Part] [float] NULL, 
CONSTRAINT [PK_Authors_Articles] PRIMARY KEY CLUSTERED 
(
    [IdAuthor] ASC, 
    [IdArticle] ASC 
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
) ON [PRIMARY] 

GO 

计算列（部分）的关键是让每个作者，即写了同一篇文章的工作的一部分。因此，例如，如果idAuthor = 1，idArticle = 1且idAuthor = 2，idArticle = 1，则 ，那么每个元素的Part必须为0.5。

感谢您的帮助！

Answer 1

CREATE TABLE [dbo].[Authors_Articles](
    [IdAuthor] [int] NOT NULL, 
    [IdArticle] [int] NOT NULL, 
CONSTRAINT [PK_Authors_Articles] PRIMARY KEY CLUSTERED 
(
    [IdAuthor] ASC, 
    [IdArticle] ASC 
)) 
GO 
create function dbo.calcPart(@IdArticle int) returns float as 
begin 
return (Select 1.0/count(*) from [Authors_Articles] where IdArticle = @IdArticle) 
end 
GO 
alter table Authors_Articles add Part as dbo.calcPart(IdArticle)