在 MS SQL Server 2008 (10.50.2811.0) Developer Edition（64 位）上，在 Windows 2008 Server 2008 R2 Standard 下运行，从 SQL Server Management Studio 中生成的脚本会创建多次删除相同约束的脚本。
一个简单的示例包括两个表，tParent 和 tChild，其中 tChild 的 ParentID 引用 tParent 的 ID。正在生成的脚本（数据库上下文菜单 => 任务 => 生成脚本...）（用于 DROP AND CREATE）如下所示：
USE [TestDb]
GO
/****** Object: ForeignKey [FK_tChild_tParent] Script Date: 08/08/2012 08:11:51 ******/
ALTER TABLE [dbo].[tChild] DROP CONSTRAINT [FK_tChild_tParent]
GO
/****** Object: Table [dbo].[tChild] Script Date: 08/08/2012 08:11:51 ******/
ALTER TABLE [dbo].[tChild] DROP CONSTRAINT [FK_tChild_tParent]
GO
DROP TABLE [dbo].[tChild]
GO
/****** Object: Table [dbo].[tParent] Script Date: 08/08/2012 08:11:52 ******/
DROP TABLE [dbo].[tParent]
GO
/****** Object: Table [dbo].[tParent] Script Date: 08/08/2012 08:11:52 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[tParent](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Name] [varchar](50) NOT NULL,
[Value] [int] NOT NULL,
CONSTRAINT [PK_tParent] PRIMARY KEY CLUSTERED
(
[ID] 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
/****** Object: Table [dbo].[tChild] Script Date: 08/08/2012 08:11:51 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[tChild](
[ID] [int] IDENTITY(1,1) NOT NULL,
[ParentID] [int] NOT NULL,
[Name] [varchar](50) NOT NULL,
[Value] [int] NOT NULL,
CONSTRAINT [PK_tChild] PRIMARY KEY CLUSTERED
(
[ID] 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
/****** Object: ForeignKey [FK_tChild_tParent] Script Date: 08/08/2012 08:11:51 ******/
ALTER TABLE [dbo].[tChild] WITH CHECK ADD CONSTRAINT [FK_tChild_tParent] FOREIGN KEY([ParentID])
REFERENCES [dbo].[tParent] ([ID])
GO
ALTER TABLE [dbo].[tChild] CHECK CONSTRAINT [FK_tChild_tParent]
GO
为什么有两条相同的行都试图删除 FK_tChild_tParent 约束？为什么两行的评论不同？