Design of Data Access Layer (DAL) is necessary for building Multi-tier web applications in ASP.Net using the best data access approach of ADO.Net. Design architecture of DAL is a main force for .Net based web applications to access the dynamic content for the presentation layer of ASP.Net web pages. Now SQL Server 2005 is considered as the best back-end for ASP.Net applications due to its compatible providers available for data access. SQL Server .Net Data Provider directly communicates with SQL Server through native data transfer protocol to access the data stored in SQL Database.

Data Access Layer for a .Net based web applications is a combination of classes, database connections, properties, get and set database values to display and save the changes into the database. Custom user Controls help in accessing the data and represent it on user interfaces through this Data Access Layer.

In ASP.Net Framework there is a key change with a replacement of old style ADO Recordset object with new components and class objects known as DataAdapter, DataSet, DataTable and DataReader. A DataAdapter has internal methods that manage to open and close the connection with database and perform the data access function to fill a DataSet.

A DataSet is a collection of DataTable objects along with relationships and constraints. DataSet has built in XML support and is an in-memory data caching object. One of a characteristic of DataSet is that it has no knowledge of the Data Source from where it is being populated coz it is a disconnected Data Access component.

Further a DataTable is a collection of rows from a single table. It is similar to the Recordset used in ADO.

See Next Designing a Data Access Layer for ASP.Net Applications