Will putting a “using” statement around a DataReader close it?

Question

I usually write my DataReader code like this:

try
{
    dr = cmd.ExecuteReader(CommandBehavior.SingleResult);
    while (dr.Read())
    {
               


        

Answer 1

Unlike the example here, my practice has been to employ a using block for the connection, the command and the reader. Note that you can stack nested using blocks to lower the indentation cost.

static void HasRows(SqlConnection connection)
{
    using (connection)
    using (SqlCommand command = new SqlCommand(
    "SELECT CategoryID, CategoryName FROM Categories;",
    connection))
    {
        connection.Open();
        using (SqlDataReader reader = command.ExecuteReader())
        {
            if (reader.HasRows)
            {
                while (reader.Read())
                {
                    Console.WriteLine("{0}\t{1}", reader.GetInt32(0),
                        reader.GetString(1));
                }
            }
            else
            {
                Console.WriteLine("No rows found.");
            }
            reader.Close();
        }   
    }
}