SQL Server-脚本，用于将数据库列从varchar更新为nvarchar（如果尚未添加nvarchar） [英] SQL Server - script to update database columns from varchar to nvarchar if not already nvarchar

问题描述

我处于必须使用脚本将现有数据库结构从varchar更新为nvarchar的情况。由于此脚本是在每次运行配置应用程序时运行的，因此，我宁愿确定是否已将列更改为nvarchar而不对表执行更改。我必须支持的数据库是SQL Server 2000、2005和2008。

I am in a situation where I must update an existing database structure from varchar to nvarchar using a script. Since this script is run everytime a configuration application is run, I would rather determine if a column has already been changed to nvarchar and not perform an alter on the table. The databases which I must support are SQL Server 2000, 2005 and 2008.

推荐答案

以下查询将为您提供所需的信息：

The following query should get you what you need:

IF EXISTS 
  (SELECT *
   FROM sysobjects syo
   JOIN syscolumns syc ON
     syc.id = syo.id
   JOIN systypes syt ON
     syt.xtype = syc.xtype
   WHERE 
     syt.name = 'nvarchar' AND
     syo.name = 'MY TABLE NAME' AND
     syc.name = 'MY COLUMN NAME')
BEGIN
   ALTER ...
END

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