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。

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();}

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";    }} 

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=52";                myCommand.ExecuteNonQuery();                myCommand.CommandText = "update P_Product set Name=‘电脑3‘                where Id=53";                myCommand.ExecuteNonQuery();                msg ="成功!";            }            catch (Exception ex)            {                msg = "失败:"+ex.Message;                          }            finally            {                myConnection.Close();            }            return msg;        }    }}