学步园

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

/*事务是一组被当作一个单元的操作，它们在执行时要么全部成功，要么全部失败。

例如转帐操作

事务的两个层次
    数据库级的事务
    ADO.NET事务
 如果在某个操作中需要对数据库进行多次更新，则必须使用事务。
SqlTransaction myTransaction
      =myConnection.BeginTransaction();
try
{     ...
       myCommand = new OleDbCommand(cmdstr,   myConnection,myTransaction);
       ...
      myTransaction.Commit();
}
catch (Exception es)
{
      myTransaction.Rollback();
}
*/
namespace Transaction
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            String connectionString = System.Configuration.ConfigurationManager.AppSettings["ConnectionString"];
            SqlConnection myconn = new SqlConnection(connectionString);

            try
            {
                myconn.Open();

                SqlTransaction myTransaction = myconn.BeginTransaction();//新建一个事务

                try
                {
                    string cmdstr = "update Account set money=money-100 where Id='1'";
                    SqlCommand mycmd = new SqlCommand(cmdstr,myconn,myTransaction);
                    mycmd.ExecuteNonQuery();

                    throw new Exception();//抛出异常，会直接被catch捕获，处理
                    string cmdstr2="update Account set money=money+100 where Id='2'";
                    SqlCommand mycmd1 = new SqlCommand(cmdstr2, myconn, myTransaction);
                    mycmd1.ExecuteNonQuery();

                    myTransaction.Commit();//只有执行这句后数据库里面的数据才有可能会改变
                }
                catch(Exception ee)
                {
                    myTransaction.Rollback();//进行回滚
                    MessageBox.Show("转账失败，正在回滚！");
                }

                myconn.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("数据库连接失败！");
            }

        }
    }
}