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/****** Object:  UserDefinedFunction [dbo].[DURATION_CALCULATION]    Script Date: 03/07/2010 05:38:31 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

-- =============================================
-- Author:	    PROUD ,RJB.PNK.U.
-- Create date: 02-ÁÕ¤-2553
-- Description:	DURATION_CALCULATION
-- =============================================
-- @VAR_DATE_TIME < Ç´» »Ñ¨¨ØºÑ¹
CREATE FUNCTION [dbo].[DURATION_CALCULATION](@VAR_DATE_TIME DATETIME)
RETURNS NVARCHAR(50)
AS
BEGIN	
	DECLARE 
		@DAY_INTERVAL		INT,
		@MONTH_INTERVAL		INT,
		@YEAR_INTERVAL		INT,
		@TEMP				INT,
		@SLIDE_BEGIN_DATE	DATETIME ,
		@SLIDE_END_DATE		DATETIME ,
		@TEMP_DATE			DATETIME ,	
		@RET_STR			NVARCHAR(50);
		
		-- BEGIN CALCULATION USE SLIDE RULE ALGOL
		SET @SLIDE_BEGIN_DATE = @VAR_DATE_TIME ;
		SET @SLIDE_END_DATE = GETDATE() ;
		SET @RET_STR = '' ;
		
		-- HOW SLIDE SHIFT ??
		IF(YEAR(@SLIDE_END_DATE)=YEAR(@SLIDE_BEGIN_DATE))
		BEGIN			
			-- DAY SHIFT 
			-- ¡·´ä»à»ç¹ÇѹÊØ´·éÒ¢ͧà´×͹·ÕèáÅéÇáÅзÓãËéà»ç¹Åºà¾×èͧèÒ¡Ѻ DATEADD
			SET @TEMP = (DAY(@VAR_DATE_TIME) - 1) *(-1) ;				
			-- ¨Ñ´´Ö§ 仢éҧ˹éÒ´éǨӹǹÇѹ·Õèà·èҡѹ
			SET @SLIDE_BEGIN_DATE = DATEADD(DAY ,@TEMP ,@VAR_DATE_TIME) ;
			SET @SLIDE_END_DATE = DATEADD(DAY ,@TEMP ,GETDATE()) ;
			
			SET @YEAR_INTERVAL = 0 ;
			SET @MONTH_INTERVAL = MONTH(@SLIDE_END_DATE) - MONTH(@SLIDE_BEGIN_DATE);
			SET @DAY_INTERVAL = DAY(@SLIDE_END_DATE) -1 ;	
						
		END
		ELSE
		BEGIN
			-- YEAR SHIFT >> SET MONTH = 1 >> JAN
			SET @SLIDE_BEGIN_DATE = dbo.DATE_SERIAL( YEAR(@VAR_DATE_TIME) ,1 ,1 ) ;
			
			-- ËÒªèǧ¡Òà SHIFT
			SET @TEMP = (DATEDIFF( DAY ,@SLIDE_BEGIN_DATE ,@VAR_DATE_TIME ) * (-1)) -1 ;
			if ((YEAR(@SLIDE_BEGIN_DATE) % 4)=0)
			BEGIN
				SET @TEMP = @TEMP+1 ; -- »Õ͸ԡÃÊØ÷Թ
			END
			
			-- ´Ö§ÇѹÊØ´·éÒÂä»à·èÒæ¡Ñ¹ << that's call slide rule
			SET @SLIDE_END_DATE = DATEADD(DAY ,@TEMP ,GETDATE() ) ;
			
			SET @RET_STR = CONVERT(VARCHAR(20) ,@SLIDE_END_DATE ,102) + '|'  ;
			-- EASY TO CALCUTION NOW
			SET @YEAR_INTERVAL = YEAR(@SLIDE_END_DATE) - YEAR(@SLIDE_BEGIN_DATE) ;
			SET @MONTH_INTERVAL = MONTH(@SLIDE_END_DATE) -1 ;		
			SET @DAY_INTERVAL = DAY(@SLIDE_END_DATE) ;
			
			-- FINE TUNE
			IF (@YEAR_INTERVAL <0)
			BEGIN
				SET @YEAR_INTERVAL = 0 ;
			END			
			
			IF ((MONTH(@SLIDE_END_DATE)=12) AND (@DAY_INTERVAL=31))
			BEGIN
				SET @YEAR_INTERVAL = @YEAR_INTERVAL +1 ;
				SET @MONTH_INTERVAL = 0 ;
				SET @DAY_INTERVAL = 0 ;
			END	
			
			
			
			--SET @TEMP_DATE = 			
		END		
				
		-- ¨Ñ´ãËéÊǧÒÁ àÈÉã´ÁÕ¤èÒà·èҡѺÈÙ¹Âì¡ç¨ÐäÁè¹ÓÍÍ¡ÊÙèÊÒµһÃЪҪ¹¤èÐ
		SET @RET_STR = '' ;
		IF ( @YEAR_INTERVAL > 0)
		BEGIN  
			SET @RET_STR = @RET_STR + CONVERT(NVARCHAR(10) ,@YEAR_INTERVAL ) + N' »Õ ';
		END			
		
		IF ( @MONTH_INTERVAL > 0)
		BEGIN  
			SET @RET_STR = @RET_STR + CONVERT(NVARCHAR(10) ,@MONTH_INTERVAL ) + N' à´×͹ ' ;
		END
			
		IF ( @DAY_INTERVAL > 0)
		BEGIN  
			SET @RET_STR = @RET_STR + CONVERT(NVARCHAR(10) ,@DAY_INTERVAL ) + N' Çѹ ' ;
		END	
				
		/* 
		-- DEBUG ONLY	
		SET @RET_STR = @RET_STR + CONVERT(VARCHAR(20) ,@DAY_INTERVAL ) + ':'
				+ CONVERT(VARCHAR(20) ,@MONTH_INTERVAL ) + ':'
				+ CONVERT(VARCHAR(20) ,@YEAR_INTERVAL )  ;
	    */
	RETURN RTRIM(LTRIM(@RET_STR)) ;

END

GO