如何在NULL列上创建唯一索引？ [英] How to create a unique index on a NULL column?

问题描述

我使用SQL Server 2005.我想限制列中的值是唯一的，同时允许NULLS。

我当前的解决方案涉及一个唯一索引

  CREATE VIEW vw_unq WITH SCHEMABINDING AS 
 SELECT Column1 
 From MyTable 
 WHERE Column1 IS NOT NULL 
 
 CREATE UNIQUE CLUSTERED INDEX unq_idx ON vw_unq（Column1）
  

有什么更好的想法吗？

解决方案

很肯定，你不能这样做，因为它违反了不重复的目的。

然而，这个人似乎有一个体面的工作：
http://sqlservercodebook.blogspot.com/2008/04/multiple-null-values-in-unique-index-in.html p>

I am using SQL Server 2005. I want to constrain the values in a column to be unique, while allowing NULLS.

My current solution involves a unique index on a view like so:

CREATE VIEW vw_unq WITH SCHEMABINDING AS
    SELECT Column1
      FROM MyTable
     WHERE Column1 IS NOT NULL

CREATE UNIQUE CLUSTERED INDEX unq_idx ON vw_unq (Column1)

Any better ideas?

解决方案

Pretty sure you can't do that, as it violates the purpose of uniques.

However, this person seems to have a decent work around: http://sqlservercodebook.blogspot.com/2008/04/multiple-null-values-in-unique-index-in.html

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