数据准备：
if exists (select * from sysobjects where id = OBJECT_ID('[classinfo]') and OBJECTPROPERTY(id, 'IsUserTable') = 1)
DROP TABLE [classinfo]
CREATE TABLE [classinfo] (
[id] [bigint] NOT NULL,
[classID] [bigint] NOT NULL,
[className] [nvarchar] (50) NOT NULL,
[stat] [varchar] (2) NOT NULL DEFAULT (1),
[autoid] [bigint] IDENTITY (1, 1) NOT NULL)
ALTER TABLE [classinfo] WITH NOCHECK ADD CONSTRAINT [PK_classinfo] PRIMARY KEY NONCLUSTERED ( [id] )
SET IDENTITY_INSERT [classinfo] ON
INSERT [classinfo] ([id],[classID],[className],[stat],[autoid]) VALUES ( 1,1,N'计算机一班',N'1',1)
INSERT [classinfo] ([id],[classID],[className],[stat],[autoid]) VALUES ( 2,2,N'计算机二班',N'1',2)