怎么使用check约束，约束密码的长度大于等于6位

[shizizuo741]

最近初学数据库，遇到约束长度的不会了。请各位大神帮忙！

注：不要用代码写，我还没学到全部用代码写的阶段。就用软件自有的check约束来写。多谢！

[---涛声依旧---]

IF  EXISTS (SELECT * FROM sys.check_constraints WHERE object_id = OBJECT_ID(N'[dbo].[CK_tbl_Test]') AND parent_object_id = OBJECT_ID(N'[dbo].[tbl_Test]'))
ALTER TABLE [dbo].[tbl_Test] DROP CONSTRAINT [CK_tbl_Test]
GO

USE [CodeRobotDB]
GO

/****** Object:  Table [dbo].[tbl_Test]    Script Date: 08/31/2014 22:14:35 ******/
IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[tbl_Test]') AND type in (N'U'))
DROP TABLE [dbo].[tbl_Test]
GO

USE [CodeRobotDB]
GO

/****** Object:  Table [dbo].[tbl_Test]    Script Date: 08/31/2014 22:14:35 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[tbl_Test](
	[UID] [varchar](20) NOT NULL,
	[PWD] [varchar](30) NOT NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

ALTER TABLE [dbo].[tbl_Test]  WITH CHECK ADD  CONSTRAINT [CK_tbl_Test] CHECK  ((len([pwd])>=(6)))
GO

ALTER TABLE [dbo].[tbl_Test] CHECK CONSTRAINT [CK_tbl_Test]
GO

[---涛声依旧---]

不用代码的： 打开查询分析器==>右键你的表名==>设计==>选中你的密码字段==>点击上面快捷按钮【管理check约束】==>弹出界面中点击添加按钮==>点击【表达式】==>输入len(pwd)>=6==>确定后保存即可

[shizizuo741]

非常感谢！成功了！