C# 4 and .NET 4

Traditional Transactions ❘ 609
ADO.NET is covered in detail in Chapter 30, “Core ADO.NET.”
TradiTional TransaCTions
Before System.Transaction was released, you could create transactions directly with ADO.NET, or you
could do transactions with the help of components, attributes, and the COM+ runtime, which is covered
in the namespace System.EnterpriseServices . To show you how the new transaction model compares to
the traditional ways of working with transactions, we present a short look at how ADO.NET transactions
and transactions with Enterprise Services are done.
ado.neT Transactions
Let ’ s start with traditional ADO.NET transactions. If you don ’ t create transactions manually, there is
a single transaction with every SQL statement. If multiple statements need to participate with the same
transaction, however, you must create a transaction manually to achieve this.
The following code segment shows how to work with ADO.NET transactions. The SqlConnection
class defi nes the method BeginTransaction() , which returns an object of type SqlTransaction . This
transaction object must then be associated with every command that participates with the transaction.
To associate a command with a transaction, set the Transaction property of the SqlCommand class
to the SqlTransaction instance. For the transaction to be successful, you must invoke the Commit()
method of the SqlTransaction object. If there is an error, you have to invoke the Rollback() method,
and every change is undone. You can check for an error with the help of a try / catch and do the rollback
inside the catch:
using System;
using System.Data.SqlClient;
using System.Diagnostics;
namespace Wrox.ProCSharp.Transactions
{
public class CourseData
{
public void AddCourse(Course course)
{
var connection = new SqlConnection(
Properties.Settings.Default.CourseManagementConnectionString);
SqlCommand courseCommand = connection.CreateCommand();
courseCommand.CommandText =
"INSERT INTO Courses (Number, Title) VALUES (@Number, @Title)";
connection.Open();
SqlTransaction tx = connection.BeginTransaction();
try
{
courseCommand.Transaction = tx;
courseCommand.Parameters.AddWithValue("@Number", course.Number);
courseCommand.Parameters.AddWithValue("@Title", course.Title);
courseCommand.ExecuteNonQuery();
tx.Commit();
}
catch (Exception ex)
{
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