A Beginner's Tutorial for Understanding Transactions and TransactionScope in ADO.NET

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Transactions;
using System.IO;

public partial class _DefaultEx : System.Web.UI.Page 
{
    readonly string CONNECTION_STRING = ConfigurationManager.ConnectionStrings["SampleDbConnectionString1"].ConnectionString;
    
    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack == false)
        {
            UpdateAmount();
        }        
    }

    protected void btnAccount1_Click(object sender, EventArgs e)
    {
        // Lets just hard code some values for demo purpose
        double amount = 0.0;
        double.TryParse(txtAmount.Text, out amount);

        PerformTransaction("2", "1", amount);
    }

    protected void btnAccount2_Click(object sender, EventArgs e)
    {   
        // Lets just hard code some values for demo purpose
        double amount = 0.0;
        double.TryParse(txtAmount.Text, out amount);

        PerformTransaction("1", "2", amount);
    }

    private void PerformTransaction(string creditAccountID, string debitAccountID, double amount)
    {
        // they will be used to decide whether to commit or rollback the transaction
        bool debitResult = false;
        bool creditResult = false;

        try
        {
            using (TransactionScope ts = new TransactionScope())
            {
                using (SqlConnection con = new SqlConnection(CONNECTION_STRING))
                {
                    con.Open();

                    // Let us do a debit first
                    using (SqlCommand cmd = con.CreateCommand())
                    {
                        cmd.CommandType = CommandType.Text;
                        cmd.CommandText = string.Format(
                            "update Account set Amount = Amount - {0} where ID = {1}",
                            amount, debitAccountID);

                        debitResult = cmd.ExecuteNonQuery() == 1;
                    }

                    // A dummy throw just to check whether the transaction are working or not
                    throw new Exception("Let see..."); // uncomment this line to see the transaction in action

                    // And now do a credit
                    using (SqlCommand cmd = con.CreateCommand())
                    {
                        cmd.CommandType = CommandType.Text;
                        cmd.CommandText = string.Format(
                            "update Account set Amount = Amount + {0} where ID = {1}",
                            amount, creditAccountID);

                        creditResult = cmd.ExecuteNonQuery() == 1;
                    }                                       

                    if (debitResult && creditResult)
                    {
                        // To commit the transaction 
                        ts.Complete();
                    }
                }
            }
        }
        catch
        {
            // the transaction scope will take care of rolling back
        }       

        UpdateAmount();
    }

    private void UpdateAmount()
    {
        // Lets show the updated balance to the user
        DataTable table = null;

        using (SqlConnection con = new SqlConnection(CONNECTION_STRING))
        {
            using (SqlCommand cmd = con.CreateCommand())
            {
                cmd.CommandType = CommandType.Text;
                cmd.CommandText = "select * from Account";

                try
                {
                    con.Open();
                    using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                    {
                        table = new DataTable();
                        da.Fill(table);
                    }
                }
                catch (Exception ex)
                {
                    throw ex;
                }
            }
        }

        if (table != null)
        {
            GridView1.DataSource = table;
            GridView1.DataBind();
        }
    }
}