.NET开发中的事务处理大比拼

本文转载：http://www.cnblogs.com/jhxk/articles/2696307.html

http://liubaolongg.blog.163.com/blog/static/21386802201222631355218/

.NET事务

• ADO.NET事务

using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MySqlServer"].ConnectionString))
{
    conn.Open();
    using (SqlTransaction tran = conn.BeginTransaction())
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            cmd.Transaction = tran;
            try
            {
                cmd.CommandText = sql1;
                cmd.ExecuteNonQuery();
                cmd.CommandText = sql2;
                cmd.ExecuteNonQuery();
                tran.Commit();
                Response.Write("Ok");
            }
            catch (SqlException ex)
            {
                tran.Rollback();
                Response.Write("Error:" + ex.Message);
            }
        }
    }
    conn.Close();
} 

    ADO.NET 显式事务占用资源少、速度快，但功能简单，只能管理单一对象和单一持久资源间的事务，比如想在数据库 B 插入失败，则回滚对数据库 A 的操作，就无法用这种 ADO.NET 显式事务来实现。 

• 隐式事务(TransactionScope)

隐式事务不具有Commit、Roolback方法。

using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MySqlServer"].ConnectionString))
{
    using (TransactionScope ts = new TransactionScope())
    {
        conn.Open();
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            try
            {
                cmd.CommandText = "insert into TranTable(Priority) values(1)";
                cmd.ExecuteNonQuery();
                cmd.CommandText = "insert into TranTable(Priority) values(256)";
                cmd.ExecuteNonQuery();
                ts.Complete();
                Response.Write("Ok");
            }
            catch (SqlException ex)
            {
                Response.Write("Error:" + ex.Message);
            }
        }
    }
    conn.Close();
} 

    TransactionScope没有和数据库直接关联，那是怎么实现用事务的方式执行语句的呢？

    如果我们在连接字符串里面加上Enlist=false;，再执行上面的代码，发现插入了一条1的记录，说明并不是以事务方式执行的。Enlist默认为true，SqlClient会自动检测是否存在事务，如果有事务，则自动登记到事务中。

• 显示事务(CommittableTransaction)

using (SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["MySqlServer"].ConnectionString))
{
    using (CommittableTransaction ct = new CommittableTransaction())
    {
        conn.Open();
        conn.EnlistTransaction(ct);//将连接登记到事务
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.Connection = conn;
            cmd.CommandType = CommandType.Text;
            try
            {
                cmd.CommandText = "insert into TranTable(Priority) values(1)";
                cmd.ExecuteNonQuery();
                cmd.CommandText = "insert into TranTable(Priority) values(256)";
                cmd.ExecuteNonQuery();
                ct.Commit();
                Response.Write("Ok");
            }
            catch (SqlException ex)
            {
                ct.Rollback();
                Response.Write("Error:" + ex.Message);
            }
        }
    }
    conn.Close();
}

• WebService(TransactionOption)

首先引用using System.EnterpriseServices;，然后设置属性TransactionOption = TransactionOption.Required。

设置TransactionOption.Disabled、TransactionOption.NotSupported、TransactionOption.Supported表示不参与事务。

设置TransactionOption.Required、TransactionOption.RequiresNew表示创建一个新的事务。意思是说当TransactionOption的属性为Required或 RequiresNew的WEB服务方法调用另一个TransactionOption的属性为Required或RequiresNew的WEB服务方法时，每个WEB服务方法将参与他们自己的事务，因为Web Service方法只能用作事务中的根对象。

PS：WEB服务方法的TransactionOption默认属性为Disabled

提交事务ContextUtil.SetComplete();

回滚事务ContextUtil.SetAbort();

[WebMethod(TransactionOption = TransactionOption.Required)]
public string HelloWorld()
{
    try
    {
        ContextUtil.EnableCommit();//开启事务
        SqlConnection con = new SqlConnection("server=.;uid=sa;pwd=sa;database=db.mdf;");
        SqlCommand cmd = new SqlCommand("update users set name = 'yangxing' where id = 5", con);
        con.Open();
        cmd.ExecuteNonQuery();
        cmd.CommandText = "update users1 set name = 'yangxing1' where id = 6";//users1表不存在，执行该语句报错
        cmd.ExecuteNonQuery();//抛出异常
        ContextUtil.SetComplete();//提交事务
        return "true";
    }
    catch
    {
        ContextUtil.SetAbort();//回滚事务
        return "false";
    }
} 

• 自动事务处理

在方法之前增加属性[AutoComplete(true)]，这样如果方法执行时没有异常就默认提交，如果有异常则这个方法就会回滚。

using System;
using System.Data.SqlClient;
using System.EnterpriseServices;//企业级服务COM+事务
namespace ClassTran
{
    [Transaction(TransactionOption.Required)]
    public class OrderData2 : ServicedComponent
    {
        //自动事务
        [AutoComplete(true)]
        public string WorkTran()
        {
            string msg = "";
            string conString = "data source=127.0.0.1;database=codematic;
               user id=sa;password=";
            SqlConnection myConnection = new SqlConnection(conString);
            myConnection.Open();
            SqlCommand myCommand = new SqlCommand();
            myCommand.Connection = myConnection;
            try
            {
                myCommand.CommandText = "update P_Product set Name='电脑2'
                     where Id=";
                myCommand.ExecuteNonQuery();
                myCommand.CommandText = "update P_Product set Name='电脑3'
                where Id=";
                myCommand.ExecuteNonQuery();
                msg ="成功!";
            }
            catch (Exception ex)
            {
                msg = "失败:"+ex.Message;
            }
            finally
            {
                myConnection.Close();
            }
            return msg;
        }
    }
}