.NET から SQL の smalldatetime への DateTime - クエリの実行方法は?

SQL Server 2008 R2 Express を使って試してみました。

これが私が書いたストアド プロシージャの例です:

CREATE PROCEDURE [dbo].[ShowGivenSmallDateTimeValue] 
    @givenSmallDateTime smalldatetime
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Simply return the given small date time value back to sender.
    SELECT @givenSmallDateTime
END
  

 この手順を実行する C# コードは次のとおりです。
 
var connectionBuilder = new SqlConnectionStringBuilder();
connectionBuilder.DataSource = "localhost\\sqlexpress";
connectionBuilder.IntegratedSecurity = true;

var now = DateTime.UtcNow;

using (var connection = new SqlConnection(connectionBuilder.ConnectionString))
using (var command = new SqlCommand())
{
    command.Connection = connection;
    command.CommandType = CommandType.StoredProcedure;
    command.CommandText = "ShowGivenSmallDateTimeValue";
    command.Parameters.Add(new SqlParameter("@givenSmallDateTime", SqlDbType.SmallDateTime) { Value = now });

    connection.Open();
    var result = (DateTime)command.ExecuteScalar();
    var difference = result - now;

    Console.WriteLine("Due to the smalldatetime roundings we have a difference of " + difference + ".");
}