Stored procedure code routines in sqlserver

In this example, there is a table in the database named StudentTable
. There are 5 columns in the table, namely
Id int,
StudentName nvarchar(50),
StudentNumber nvarchar(20),
Age int,
Class nvarchar(50) The
stored procedure codes are as follows, including New, deleted, and modified functions:

USE [MySqlDataBase] --我的数据库名为MySqlDataBase，添加这行表示在MySqlDataBase数据库中执行下面代码
GO

if exists (select * from sysobjects where id = object_id(N'PROC_UpdateTable') and type in (N'P', N'PC'))
drop procedure PROC_UpdateTable --在数据库中执行本文件代码的时候，如果存在名为PROC_UpdateTable的存储过程则将旧的存储过程删除
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:		Bruce
-- Description:	操作表格
-- =============================================
CREATE PROCEDURE [dbo].[PROC_UpdateTable](
	@OperType int, --操作类型（0-不操作，1-新增，2-删除，3-修改
	@Id int,
	@StudentName nvarchar(50),
	@StudentNumber nvarchar(20),
	@Age int,
	@Class nvarchar(50)
)--本存储过程包含上述参数，可以由客户端程序将参数传给本存储过程
AS
	declare @maxid int
BEGIN
	--使返回的结果中不包含有关受 Transact-SQL 语句影响的行数的信息
	SET NOCOUNT ON;
    --如果外部存在事务则不执行存储过程
	if((@@trancount<>0) or (@OperType = 0))
		return 1
	--如果 Transact-SQL 语句产生运行时错误，整个事务将终止并回滚
	set xact_abort on 
		if(@OperType = 1) --新增
			begin
			begin tran maintran
			insert into StudentTable values(@StudentName,@StudentNumber,@Age,@Class);
					if(@@ERROR <> 0)
					begin
						rollback tran maintran
						return 4 -- 失败，回滚
					end
			commit tran miantran			
			return 0
			end	
		else if(@OperType = 2)	--删除
			begin
			begin tran maintran
				delete from StudentTable where ID=@Id;
				if(@@ERROR <> 0)
					begin
						rollback tran maintran
						return 4 -- 失败，回滚
					end
			commit tran miantran
			return 0
			end
		else if(@OperType = 3)	--修改
			begin
			begin tran maintran
				update StudentTable set StudentName=@StudentName,StudentNumber=@StudentNumber,Age=@Age,Class=@Class where ID=@Id;
				if(@@ERROR <> 0)
					begin
						rollback tran maintran
						return 4 -- 失败，回滚
					end
			commit tran miantran
			return 0
			end
END