We now have a library that supply’s all the required functionality to  add, subtract and display a balance, also display the history of each transaction.

we now need to decide how to save this data, I could simply serialize the collection and balance to an xml file, but I want to use this data in the future, on the next project where I can budget using known data from the past.

ok so it seams that a sql database would be in order. a simple table should do for the minute. along with the usual select, insert, update and delete stored procedures

USE [MoneyEngine]
GO
/****** Object:  Table [dbo].[tTransactions]    Script Date: 01/01/2007 20:28:20 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tTransactions](
    [TransID] [bigint] IDENTITY(1,1) NOT NULL,
    [TransType] [int] NOT NULL,
    [TransDate] [datetime] NOT NULL,
    [TransCategory] [nvarchar](max) NULL,
    [TransDescription] [nvarchar](max) NULL,
    [TransAmount] [money] NULL
) ON [PRIMARY]

GO
SET ANSI_PADDING OFF

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USE [MoneyEngine]
GO
/****** Object:  StoredProcedure [dbo].[uspSelectTransactionsDateOrder]    Script Date: 01/01/2007 20:29:50 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:        Duncan
-- Create date: 1/1/2007
-- Description:    Select all transactions
-- =============================================
CREATE PROCEDURE [dbo].[uspSelectTransactionsDateOrder] 

AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    SELECT TransID, TransType, TransDate, TransCategory, TransDescription, TransAmount

    FROM tTransactions

    ORDER BY TransDate
END

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USE [MoneyEngine]
GO
/****** Object:  StoredProcedure [dbo].[uspInsertTransaction]    Script Date: 01/01/2007 20:39:25 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:        Duncan
-- Create date: 1/1/2007
-- Description:    insert a new transaction
-- =============================================
CREATE PROCEDURE [dbo].[uspInsertTransaction] 
    -- Add the parameters for the stored procedure here
    @TransType            INT,
    @TransDate            DATETIME,
    @TransCategory        NVARCHAR(MAX),
    @TransDescription    NVARCHAR(MAX),
    @TransAmount        MONEY,
    @TransID            BIGINT OUTPUT

AS
BEGIN
    INSERT INTO tTransactions(TransType, TransDate, TransCategory, TransDescription, TransAmount)
    VALUES(@TransType, @TransDate, @TransCategory, @TransDescription, @TransAmount)

    SET @TransID = @@IDENTITY
END

USE [MoneyEngine]
GO
/****** Object:  StoredProcedure [dbo].[uspUpdateTransaction]    Script Date: 01/01/2007 20:41:03 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:        Duncan
-- Create date: 1/1/2007
-- Description:    Update a transaction
-- =============================================
CREATE PROCEDURE [dbo].[uspUpdateTransaction] 
    -- Add the parameters for the stored procedure here
    @TransID            BIGINT,
    @TransType            INT,
    @TransDate            DATETIME,
    @TransCategory        NVARCHAR(MAX),
    @TransDescription    NVARCHAR(MAX),
    @TransAmount        MONEY

AS
BEGIN

    UPDATE tTransactions

    SET TransType = @TransType,
        TransDate = @TransDate,
        TransCategory = @TransCategory,
        TransDescription = @TransDescription,
        TransAmount = @TransAmount

    WHERE TransID = @TransID
        
END

USE [MoneyEngine]
GO
/****** Object:  StoredProcedure [dbo].[uspDeleteTransaction]    Script Date: 01/01/2007 20:53:09 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:        Duncan
-- Create date: 1/1/2007
-- Description:    Delete a transaction
-- =============================================
CREATE PROCEDURE [dbo].[uspDeleteTransaction] 
    -- Add the parameters for the stored procedure here
    @TransID INT 

AS
BEGIN
    DELETE 

    FROM tTransactions
    
    WHERE TransID = @TransID
END

Of cause each of these stored procedures will need to be given permission to execute, and then its back to the 

code to write the data access layer.