使用系统.Data代替System.Data.SqlClient

我有一个如何使用System.Data和System.Data.SqlClient的问题。

在下面的例子中，我使用了System.Data.SqlClient命名空间。我可以在这里写System.Data而不是System.Data.SqlClient，因为SqlClient是已经包含在System.Data命名空间中的 ?

using System;
using System.Data.SqlClient;
class Program
{
    static void Main()
    {
    // First access the connection string.
    // ... This may be autogenerated in Visual Studio.
    string connectionString =
                     ConsoleApplication1.Properties.Settings.Default.ConnectionString;
    //
    // In a using statement, acquire the SqlConnection as a resource.
    //
    using (SqlConnection con = new SqlConnection(connectionString))
    {
        //
        // Open the SqlConnection.
        //
        con.Open();
        //
        // The following code uses an SqlCommand based on the SqlConnection.
        //
        using (SqlCommand command = new SqlCommand("SELECT TOP 2 * FROM Dogs1", con))
        using (SqlDataReader reader = command.ExecuteReader())
        {
          while (reader.Read())
          {
            Console.WriteLine("{0} {1} {2}",
            reader.GetInt32(0), reader.GetString(1), reader.GetString(2));
          }
        }
    }
  }
}