在数据库连接上创建事务处理对象，然后调用事务处理对象来提交事务或回滚事务。简单的代码：

private void button1_Click(object sender, System.EventArgs e)
  {
   SqlConnection conn = new SqlConnection("Data Source=192.168.2.200;uid=sa; password=;database = HaierHR");
   conn.Open();
   //启用事务
   SqlTransaction tran = conn.BeginTransaction();
   SqlCommand cmd = new SqlCommand();
   cmd.Connection = conn;
   cmd.Transaction = tran;
   try
   {
    cmd.CommandText = "UPDATE HRRollMain Set TotalMember=TotalMember-100 WHERE RollID = '2005070101'";
    cmd.ExecuteNonQuery();
    cmd.CommandText = "UPDATE HRRollSum Set TotalSumMember=TotalSumMember+100 WHERE RollSumID = '20050701'";
    cmd.ExecuteNonQuery();
    tran.Commit();
    MessageBox.Show("事务提交成功！");
   }
   catch(Exception ex)
   {
    tran.Rollback();
    MessageBox.Show("Error!"+ex.Message);
   }   
  }