Programming C#, Second Edition

Getting Started with ADO.NET

Enough theory! Let’s write some code and see how this works. Working with ADO.NET can be complex, but for many queries, the model is surprisingly simple.

In this example, create a simple Windows Form, with a single list box in it called lbCustomers. Populate this list box with bits of information from the Customers table in the Northwind database.

Begin by creating a DataAdapter object:

SqlDataAdapter DataAdapter = 
new SqlDataAdapter(
commandString, connectionString);

The two parameters are commandString and connectionString. The commandString is the SQL statement that will generate the data you want in your DataSet:

string commandString = 
    "Select CompanyName, ContactName from Customers";

The connectionString is whatever string is needed to connect to the database. In my case, I’m running SQL Server on my development machine where I have left the system administrator (sa) password blank (I know, I know, not a good idea. I’ll fix it by the time this book is released. Honest.):

string connectionString = 
    "server=localhost; uid=sa; pwd=; database=northwind";

If you do not have SQL Server installed, select Samples and Quickstart Tutorials from the Microsoft .NET Framework SDK program group. A web page appears, giving you the option to install the .NET Framework Samples Database, which includes an installation of SQL Server. After you install the samples database, set up the QuickStarts (this will create the northwind sample database). To use this database, ...