Manejar Transacciones en la Base de Datos desde C# .Net y Visual Basic .Net

CREATE TABLE [dbo].[Cliente](
	[Codigo] [int] IDENTITY(1,1) NOT NULL,
	[Nombre] [varchar](50) NOT NULL,
	[Apellido] [varchar](50) NOT NULL,
	[DocumentoNro] [varchar](50) NOT NULL,
	[Direccion] [varchar](50) NULL,
	[Telefono] [varchar](50) NULL,
	[Email] [varchar](50) NULL,
	[FechaNacimiento] [date] NOT NULL,
 CONSTRAINT [PK_Persona] PRIMARY KEY CLUSTERED
(
	[Codigo] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
 
GO
CREATE TABLE [dbo].[CtaCte](
	[NroCuenta] [int] NOT NULL,
	[CodCliente] [int] NOT NULL,
	[Saldo] [money] NOT NULL,
 CONSTRAINT [PK_CtaCte] PRIMARY KEY CLUSTERED
(
	[NroCuenta] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]
 
GO
 
ALTER TABLE [dbo].[CtaCte]  WITH CHECK ADD  CONSTRAINT [FK_CtaCte_Cliente] FOREIGN KEY([CodCliente])
REFERENCES [dbo].[Cliente] ([Codigo])
GO
 
ALTER TABLE [dbo].[CtaCte] CHECK CONSTRAINT [FK_CtaCte_Cliente]
GO
 
ALTER TABLE [dbo].[CtaCte] ADD  CONSTRAINT [DF_CtaCte_Saldo]  DEFAULT ((0)) FOR [Saldo]
GO

        ' instancia de la conexion
        Dim conn As SqlClient.SqlConnection = New SqlClient.SqlConnection("Data Source=127.0.0.1;Initial Catalog=DevTroce;User Id=sa;Password=******")
        ' objeto transaccional
        Dim tran As SqlClient.SqlTransaction = Nothing
        ' string para transaccion
        Dim strSQL As String = "Update CtaCte set Saldo = Saldo - 40000 where NroCuenta = 100002"
        ' objeto command para ejecucion del query
        Dim command As SqlClient.SqlCommand = New SqlClient.SqlCommand
        ' seteo de atributos del command
        With command
            .Connection = conn
            .CommandType = CommandType.Text
            .CommandTimeout = 0
            .CommandText = strSQL
        End With
 
        Try
            ' abrir conexion
            If conn.State <> ConnectionState.Open Then
                conn.Open()
            End If
            ' comenzamos la transaccion
            tran = conn.BeginTransaction()
            ' asignamos transaccion al command
            command.Transaction = tran
            ' ejecutamos la resta de la transferencia
            command.ExecuteNonQuery()
            ' preparamos la suma del dinero a la otra cuenta
            strSQL = "Update CtaCte set Saldo = Saldo + 40000 where NroCuenta = 100001"
            ' reasignamos es string sql al command
            command.CommandText = strSQL
            ' ejecutamos la suma
            command.ExecuteNonQuery()
            ' si todo salio bien commiteamos los cambios
            tran.Commit()
            ' Emitimos el aviso exitoso
            MessageBox.Show("> Transaccion Exitosa :D")
        Catch ex As Exception
            ' si algo fallo deshacemos todo
            tran.Rollback()
            ' mostramos el mensaje de error
            MessageBox.Show(ex.Message)
        Finally
            ' cerramos la conexion
            If conn.State <> ConnectionState.Closed Then
                conn.Close()
            End If
            ' destruimos la conexion
            conn.Dispose()
        End Try

            // instancia de la conexion
            SqlConnection conn = new SqlConnection("Data Source=127.0.0.1;Initial Catalog=DevTroce;User Id=sa;Password=******");
            // objeto transaccional
            SqlTransaction tran = null;
            // string para transaccion
            string strSQL = "Update CtaCte set Saldo = Saldo + 40000 where NroCuenta = 100002";
            // objeto command para ejecucion del query
            SqlCommand command = new SqlCommand();
            // seteo de atributos del command
            command.Connection = conn;
            command.CommandType = CommandType.Text;
            command.CommandTimeout = 0;
            command.CommandText = strSQL;
 
            try
            {
                // abrir la conexion
                if (conn.State != ConnectionState.Open)
                    conn.Open();
                // comenzamos la transaccion
                tran = conn.BeginTransaction();
                // asignamos transaccion al command
                command.Transaction = tran;
                // ejecutamos la suma de la transferencia
                command.ExecuteNonQuery();
                // preparamos la resta del dinero a la otra cuenta
                strSQL = "Update CtaCte set Saldo = Saldo - 40000 where NroCuenta = 100001";
                // reasignamos el string sql al command
                command.CommandText = strSQL;
                // ejecutamos la resta
                command.ExecuteNonQuery();
                // si todo salio bien commiteamos los cambios
                tran.Commit();
                // emitimos el aviso exitoso
                MessageBox.Show("> Transaccion Exitosa :D");
            }
            catch (Exception ex)
            {
                // si algo fallo deshacemos todo
                tran.Rollback();
                // mostramos el mensaje del error
                MessageBox.Show(ex.Message);
            }
            finally
            {
                // cerramos la conexion
                if (conn.State != ConnectionState.Closed)
                    conn.Close();
                // destruimos la conexion
                conn.Dispose();
            }