indexertest.cs

来自「Professional C# 2nd Edition」· CS 代码 · 共 64 行

using System;
using System.Data.OleDb;

public class SimpleSelect
{
	public static	int	Main(string[] args)
	{
		string		  source = "Provider=SQLOLEDB;"	+ Login.Connection ;

		string		  select = "SELECT CategoryID,CategoryName FROM	Categories"	;

		using ( OleDbConnection	conn = new OleDbConnection ( source	) )
		{
			conn.Open()	;

			OleDbCommand	cmd	= new OleDbCommand ( select	, conn ) ;

			OleDbDataReader	aReader	= cmd.ExecuteReader	( )	;

			aReader.Read ( ) ;

			// Now time	access to the first	field in the reader...
			long timeInitial , timeElapsed , iterations	, maxIterations	= 1000000;

			int	  theCategoryID	;

			timeInitial	= DateTime.Now.Ticks ;

			for	( iterations = 0 ; iterations <	maxIterations ;	iterations++ )
				theCategoryID	= (int)	aReader[0] ;

			timeElapsed	= DateTime.Now.Ticks ;	  

			Console.WriteLine (	"{0} iterations	using numeric indexer :	{1}s" ,	
				iterations ,
				new	TimeSpan ( timeElapsed - timeInitial ) ) ;

			timeInitial	= DateTime.Now.Ticks ;

			for	( iterations = 0 ; iterations <	maxIterations ;	iterations++ )
				theCategoryID	= (int)	aReader["CategoryID"] ;
			
			timeElapsed	= DateTime.Now.Ticks ;	  

			Console.WriteLine (	"{0} iterations	using textual indexer :	{1}s" ,	
				iterations ,
				new	TimeSpan ( timeElapsed - timeInitial )	) ;

			timeInitial	= DateTime.Now.Ticks ;

			for	( iterations = 0 ; iterations <	maxIterations ;	iterations++ )
				theCategoryID	= aReader.GetInt32 (0);
			
			timeElapsed	= DateTime.Now.Ticks ;	  

			Console.WriteLine (	"{0} iterations	using GetInt32(0)	  :	{1}s" ,	
				iterations ,
				new	TimeSpan ( timeElapsed - timeInitial )	) ;
		}
			
		return 0;
	}
}