Tài liệu Writing Database-Independent Code doc

[ Team LiB ]

Recipe 1.11 Writing Database-Independent Code

Problem

You need to develop an application that can be used with different data providers, but

does not lose functionality that is specific to the different providers. You want to create

provider-independent code and use it with the provider-specific code that you might

need.

Solution

The solution shows how to use interfaces that are inherited by .NET connected classes

(such as Connection and DataReader) to create provider-independent code that can be

used with provider-specific code to access unique functionality.

The sample code contains a method and two event handlers:

GetData( )

This method is a .NET data provider-independent method that accepts .NET data

provider-specific Connection and DataAdapter arguments as generic

IDbConnection and IDbDataAdapter interface types. The interfaces are used to fill

a DataSet from the Customers table in Northwind. The default view of the

Customers DataTable is bound to the data grid on the form.

Finally, the provider-specific Connection for the IDbConnection is identified and

provider-specific logic executed.

SQL Button.Click

This event handler is provider-specific code that creates a SqlConnection and a

SqlDataAdapter object and passes them as arguments into the provider￾independent GetData( ) method.

OLE DB Button.Click

This event handler is provider-specific code that creates an OleDbConnection and

an OleDbDataAdapter object and passes them as arguments into the provider￾independent GetData( ) method.

The C# code is shown in Example 1-9.