Data Access Layer

Download

• Binary ATTDAL1-1-BIN.zip
• Source ATTDAL1-1-SOURCE.zip

Overview

This data access layer is a Microsoft .Net 2.0 object library that helps abstract away the data access part of any .Net application.

 

The main benefits of using this access layer:

 

• Facilitates good data access practices
• Enforces C.R.U.D database operations
• Allows you to program against one object model for any database vendor
• Improves productivity by reducing the amount of code written
• Improves maintainability by centralizing all data access code

 

Class Diagram

 

 

 

Example of Data Access

 

This example shows how to use the data access layer to return records from the AdventureWorks database that comes with Microsoft SQL Server 2005.

 

First we create our DAL object, we are using MS SQL Server so we use the DALMSSQL object.

 

String connectionString = @”Data Source=LEEMCE2005\SQLEXPRESS;Initial Catalog=AdventureWorks;Integrated Security=True”;

DALMSSQL dal = new DALMSSQL(connectionString, DataAccess.ConnectStringType.String, DataAccess.ApplicationType.Windows);

 

In this constructor we tell the DALMSSQL object that we are passing it a raw connection string and we are accesing it from a Windows application.

 

Next we need to create our parameter objects to pass to our stored procedure.

           

Parameters parameters = new Parameters();

Parameter managerId = new Parameter(“@ManagerID”, “197″);

parameters.Add(managerId);

 

Now we have a collection of parameters we can call the stored procedure as follows

 

SqlDataReader reader = (SqlDataReader)dal.ReadRecords(“uspGetManagerEmployees”, parameters);

 

We now have a DataReader object containing the returned records, because the DALMSSQL ReadRecords method return a IDataReader interface we need to cast this to a SqlDataReader.

 

Now the interesting bit is, if we decided to change our database to use MySQL instead of MS SQL then the only line we would need to change is

 

DALMSSQL dal = new DALMSSQL

to

DALMYSQL dal = new DALMYSQL

And thats all there is to it

Database’s supported

• Microsoft SQL Server
• MySQL

Licence for use

This software is licenced under the GNU General Public License Version 2 which can be read by clicking the link.

Please let me know your comments on the software and feel free to modify and use as you wish. If you do improve the software then please email me back the source code for inclusion in the released version.