Build Your Own ASP.NET 2.0 Web Site Using C# & VB, Second Edition

❑

how to execute SQL queries and retrieve their results using ADO.NET

❑

how to display data that is read from a database

❑

how to handle data access errors

Introducing ADO.NET

In previous chapters, we learned how to use Visual Web Developer and SQL

Management Studio to connect to a database and execute SQL queries. Now,

it’s time to apply this knowledge. Within our web application, we’ll use

ADO.NET’s classes to connect to the database; we’ll then use that connection

to execute SQL queries.

ADO.NET 2.0 and Generic Data Access

ADO.NET is able to use different types of data connections, depending on

the kind of database to which the application is trying to connect. The

ADO.NET classes whose names start with Sql (such as the previously

mentioned SqlConnection, SqlCommand, etc.) are specifically built to

connect to SQL Server.

Similar classes are provided for other databases—for example, if you’re

working with Oracle, you can use classes such as OracleConnection,

OracleCommand, and so on. If, on the other hand, you’re working with

database systems for which such classes are not specifically designed, you

can use generic low-level interfaces; most databases can be accessed through

the OLE DB interface (using classes such as OleDbConnection and

OleDbCommand), or the older ODBC interface (using classes such as

OdbcConnection and OdbcCommand).

In this book, we’ll use only the Sql classes, but it’s good to know that you

have options!

In order to use ADO.NET, we must first decide which kind of database we’ll use,

and import those namespaces containing classes that work with the database.

Since we’re using SQL Server, you’ll need to import the System.Data.SqlClient

namespace. This contains all the required Sql classes, the most important of

which are:

SqlConnection

This class exposes properties and methods for connecting to an SQL Server

database.

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Chapter 9: ADO.NET