访问web.config中数据库连接字符串

ConfigurationManager 成员
提供对客户端应用程序配置文件的访问。无法继承此类。

private DataSet RunQuery(SqlCommand sqlQuery)
    {
        string connectionString =
            ConfigurationManager.ConnectionStrings
            ["NorthwindConnectionString"].ConnectionString;
        SqlConnection DBConnection =
            new SqlConnection(connectionString);
        SqlDataAdapter dbAdapter = new SqlDataAdapter();
        dbAdapter.SelectCommand = sqlQuery;
        sqlQuery.Connection = DBConnection;
        DataSet resultsDataSet = new DataSet();
        try
        {
            dbAdapter.Fill(resultsDataSet);
        }
        catch
        {
            labelStatus.Text = "Unable to connect to SQL Server.";
        }
        return resultsDataSet;
    }

// Get connectionStrings.
static void GetConnectionStrings()
{
    // Get the connectionStrings.
    ConnectionStringSettingsCollection connectionStrings =
         ConfigurationManager.ConnectionStrings;

    // Get the collection enumerator.
    IEnumerator connectionStringsEnum =
        connectionStrings.GetEnumerator();

    // Loop through the collection and 
    // display the connectionStrings key, value pairs.
    int i = 0;
    Console.WriteLine("Connection strings.");
    while (connectionStringsEnum.MoveNext())
    {
        string name = connectionStrings[i].Name;
        Console.WriteLine("Name: {0} Value: {1}",
        name, connectionStrings[name]);
        i += 1;
    }

}