C# DateDiff ฟังก์ชั่นคำนวนอายุ C# ,Extension method ,MS SQL และ MySQL

public class DateDifference
{
    private DateTime _FromDate;
    private DateTime _ToDate;
    private int _Year = 0;
    private int _Month = 0;
    private int _Day = 0;

    public int Year
    {
        get { return _Year; }
        set { _Year = value; }
    }
    public int Month
    {
        get { return _Month; }
        set { _Month = value; }
    }
    public int Day
    {
        get { return _Day; }
        set { _Day = value; }
    }
    public DateTime FromDate
    {
        get { return _FromDate; }
        set { _FromDate = value; }
    }
    public DateTime ToDate
    {
        get { return _ToDate; }
        set { _ToDate = value; }
    }

    /// <summary>
    /// defining Number of days in month; index 0=> january and 11=> December
    /// february contain either 28 or 29 days, that's why here value is -1
    /// which wil be calculate later.
    /// </summary>
    private int[] monthDay = new int[12] { 31, -1, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

    public DateDifference(DateTime argFromDate)
    {
        _ToDate = DateTime.Now;
        _FromDate = argFromDate;
        CalcDifferenceDate();
    }

    public DateDifference(DateTime argFromDate, DateTime argToDate)
    {
        _ToDate = argToDate;
        _FromDate = argFromDate;
        CalcDifferenceDate();
    }

    private void SwapDate(ref DateTime LeftDate, ref DateTime RightDate)
    {
        DateTime tempDate;
        if (LeftDate > RightDate)
        {
            tempDate = LeftDate;
            LeftDate = RightDate;
            RightDate = tempDate;
        }
        else
        {
            LeftDate = LeftDate;
            RightDate = RightDate;
        }
    }

    private void CalcDifferenceDate()
    {

        SwapDate(ref _FromDate, ref _ToDate);
        int carryFlag = 0;

        // ***************************
        // Day calculation 
        if (this.FromDate.Day > this.ToDate.Day)
            carryFlag = this.monthDay[this.FromDate.Month - 1];

        // febuary detect
        if (carryFlag == -1)
        {
            if (CheckedLeapYear(this.FromDate))
                // leap year february contain 29 days
                carryFlag = 29;
            else
                carryFlag = 28;
        }

        if (carryFlag != 0)
        {
            this.Day = (this.ToDate.Day + carryFlag) - this.FromDate.Day;
            carryFlag = 1;
        }
        else
            this.Day = this.ToDate.Day - this.FromDate.Day;

        // ***************************
        // Month calculation 

        if ((this.FromDate.Month + carryFlag) > this.ToDate.Month)
        {
            this.Month = (this.ToDate.Month + 12) - (this.FromDate.Month + carryFlag);
            carryFlag = 1;
        }
        else
        {
            this.Month = this.ToDate.Month - (this.FromDate.Month + carryFlag);
            carryFlag = 0;
        }

        this.Year = this.ToDate.Year - (this.FromDate.Year + carryFlag);
    }

    private bool CheckedLeapYear(DateTime checkedDate)
    {
        int myYear = checkedDate.Year;
        return (((myYear % 4) == 0) && ((myYear % 100) != 0) || ((myYear % 400) == 0));
    }

    public string ToString(string argYearUnit, string argMonthUnit, string argDayUnit)
    {
        string retStr = string.Empty;
        if (this.Year > 0)
            retStr = retStr + string.Format("{0} {1} ", this.Year.ToString("#,##0"), argYearUnit);
        if (this.Month > 0)
            retStr = retStr + string.Format("{0} {1} ", this.Month.ToString("#,##0"), argMonthUnit);
        if (this.Day > 0)
            retStr = retStr + string.Format("{0} {1} ", this.Day.ToString("#,##0"), argDayUnit);
        return retStr.Trim();
    }

    public override string ToString()
    {
        return this.ToString("Year(s)", "Month(s)", "Day(s)");
    }
}

namespace GeneralExtension
{

    public static class MyExtension
    {

        public static AgeSpan CalcAge(this DateTime Am, DateTime argToDate)
        {
            DateTime FromDate = Am;
            DateTime ToDate = argToDate;
            DateTime tempDate = DateTime.Now;

            AgeSpan retAge = new AgeSpan();

            int CarryFlag = 0;

            if (Am > argToDate)
            {
                ToDate = Am;
                FromDate = argToDate;
            }
            else
            {
                ToDate = argToDate;
                FromDate = Am;
            }

            // Day calc
            if (FromDate.Day > ToDate.Day)
            {
                // Get last day of month from previous month
                // even if leapyear system will automate return correctly
                tempDate = new DateTime(FromDate.Year, FromDate.Month, 1);
                tempDate = (tempDate.AddMonths(1)).AddDays(-1);

                CarryFlag = tempDate.Day;
                retAge.Day = (ToDate.Day + CarryFlag) - FromDate.Day;
                CarryFlag = 1;
            }
            else
                retAge.Day = ToDate.Day - FromDate.Day;

            //month calc
            if ((FromDate.Month + CarryFlag) > ToDate.Month)
            {
                retAge.Month = (ToDate.Month + 12) - (FromDate.Month + CarryFlag);
                CarryFlag = 1;
            }
            else
            {
                retAge.Month = ToDate.Month - (FromDate.Month + CarryFlag);
                CarryFlag = 0;
            }

            retAge.Year = ToDate.Year - (FromDate.Year + CarryFlag);

            return retAge;

        }

        public static AgeSpan CalcAge(this DateTime Am)
        {
            return Am.CalcAge(DateTime.Now);
        }
    }
    public class AgeSpan
    {
        public int Year { get; set; }
        public int Month { get; set; }
        public int Day { get; set; }

        public AgeSpan() { this.Year = 0; this.Month = 0; this.Day = 0; }

        public override string ToString()
        {
            return this.ToString("Year(s)", "Month(s)", "Day(s)", " ,");
        }

        public string ToString(string argYearCaption, string argMonthCaption, string argDayCaption, string argSeparator)
        {
            string strRet = string.Empty;

            if (Year > 0)
                strRet = string.Format("{0} {1}", this.Year, argYearCaption, argSeparator);
            if (Month > 0)
            {
                if(strRet.Length > 0 ) strRet = strRet + argSeparator ;
                strRet = strRet + string.Format("{0} {1}", this.Month, argMonthCaption, argSeparator);
            }
            if (Day > 0)
            {
                if (strRet.Length > 0) strRet = strRet + argSeparator;
                strRet = strRet + string.Format("{0} {1}", this.Day, argDayCaption);
            }
            return strRet;
        }
    }
}

/****** Object:  UserDefinedFunction [dbo].[RPAD]    Script Date: 09/29/2010 05:54:19 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

-- =============================================
-- Author:		PROUD
-- Create date: <Create Date, ,>
-- Description:	<Description, ,>
-- =============================================
CREATE FUNCTION [dbo].[RPAD] (@VAR_STR NVARCHAR(MAX) ,@VAR_LENGTH INT ,@VAR_FILL_CHAR NVARCHAR(MAX))
	RETURNS NVARCHAR(MAX)

AS
BEGIN

	DECLARE
		@TEMP			INT , 
		@COUNTER		INT ,
		@RETSTR			NVARCHAR(MAX) ;
		
	SET @TEMP = @VAR_LENGTH - LEN(@VAR_STR);
	SET @RETSTR = @VAR_STR ;
	IF (@TEMP>0)
	BEGIN
		SET @COUNTER = 0;
		WHILE (@COUNTER < @TEMP)
		BEGIN
			SET @RETSTR = @RETSTR + @VAR_FILL_CHAR ;
			SET @COUNTER = @COUNTER +1 ;
		END
	END	
					
	RETURN @RETSTR 

END

GO

/****** Object:  UserDefinedFunction [dbo].[LPAD]    Script Date: 09/29/2010 05:55:06 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

-- =============================================
-- Author:		PROUD
-- Create date: <Create Date, ,>
-- Description:	<Description, ,>
-- =============================================
CREATE FUNCTION [dbo].[LPAD] (@VAR_STR NVARCHAR(MAX) ,@VAR_LENGTH INT ,@VAR_FILL_CHAR NVARCHAR(MAX))
	RETURNS NVARCHAR(MAX)

AS
BEGIN

	DECLARE
		@TEMP			INT , 
		@COUNTER		INT ,
		@RETSTR			NVARCHAR(MAX) ;
		
	SET @TEMP = @VAR_LENGTH - LEN(@VAR_STR);
	SET @RETSTR = @VAR_STR ;
	IF (@TEMP>0)
	BEGIN
		SET @COUNTER = 0;
		WHILE (@COUNTER < @TEMP)
		BEGIN
			SET @RETSTR = @VAR_FILL_CHAR + @RETSTR ;
			SET @COUNTER = @COUNTER +1 ;
		END
	END	
					
	RETURN @RETSTR 

END

GO

/****** Object:  UserDefinedFunction [dbo].[DATE_SERIAL]    Script Date: 09/29/2010 05:55:31 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

-- ======================================================
-- Author:        <PROUD ,PRANAKHON RAJABHUTNUNIVERSITY>
-- Create date:   <12 DEC 2009>
-- Description:   <CREATE DATETIME WITH EXACTLY FORMAT>
-- ======================================================
CREATE FUNCTION [dbo].[DATE_SERIAL](@VAR_YEARPART INT ,@VAR_MONTHPART INT ,@VAR_DAYPART INT)
RETURNS DATETIME
AS
BEGIN	
	DECLARE 
		
		@TEMP_STR			VARCHAR(20) ,
		@RET_DATE			DATETIME;
		
		-- BEGIN CALCULATION 
		
		SET @TEMP_STR = CONVERT(VARCHAR ,@VAR_DAYPART) + '-'
			+ CONVERT(VARCHAR ,@VAR_MONTHPART) + '-'
			+ CONVERT(VARCHAR ,@VAR_YEARPART) ;
		SET @RET_DATE = CONVERT(DATETIME ,@TEMP_STR ,105) ;	
	
	RETURN @RET_DATE  ;

END

/****** Object:  UserDefinedFunction [dbo].[CALC_AGE]    Script Date: 09/29/2010 05:56:26 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- ======================================================
-- Author:        <PROUD ,PRANAKHON RAJABHUTNUNIVERSITY>
-- Create date:   <25 SEPT2010>
-- Description:   <CALC PRECISE AGE>
-- ======================================================
CREATE FUNCTION [dbo].[CALC_AGE] 
(
	-- Add the parameters for the function here
	@VAR_FROM_DATE DATETIME ,@VAR_TO_DATE DATETIME ,@OUTPUT_PATTERN INT
)
RETURNS VARCHAR(100)
AS
BEGIN
	-- Declare the return variable here
	DECLARE @TEMP				INT ;
	DECLARE @FROM_DATE			DATETIME ;
	DECLARE @TO_DATE			DATETIME ;
	DECLARE @TEMP_DATE			DATETIME ;
	DECLARE @CARRY_FLAG			INT ;
	DECLARE @MY_YEAR			INT ;
	DECLARE @MY_MONTH			INT ;
	DECLARE @MY_DAY				INT ;
	DECLARE @RET_STR			VARCHAR(100) ;
	
	SET @CARRY_FLAG = 0 ;
	
	-- REORDER
	IF (DATEDIFF(DAY ,@VAR_FROM_DATE ,@VAR_TO_DATE) >= 0 )
	BEGIN
		SET @FROM_DATE = @VAR_FROM_DATE;
		SET @TO_DATE = @VAR_TO_DATE ;
	END 
	ELSE
	BEGIN
		SET @FROM_DATE = @VAR_TO_DATE;
		SET @TO_DATE = @VAR_FROM_DATE ;
	END ;
	
	-- DAY CALCULATION
	IF (DAY(@FROM_DATE) > DAY(@TO_DATE))
	BEGIN
		SET @TEMP_DATE = dbo.DATE_SERIAL(YEAR(@FROM_DATE) ,MONTH(@FROM_DATE) ,1) ;
		SET @TEMP_DATE = DATEADD(MONTH ,1 ,@TEMP_DATE) ;
		SET @TEMP_DATE = DATEADD(DAY ,-1 ,@TEMP_DATE) ;
		SET @CARRY_FLAG = DAY(@TEMP_DATE) ;
		SET @MY_DAY = (DAY(@TO_DATE) + @CARRY_FLAG) - DAY(@FROM_DATE) ;
		SET @CARRY_FLAG = 1 ;
	END
	ELSE	
		SET @MY_DAY = DAY(@TO_DATE) - DAY(@FROM_DATE) ;	
	
	-- MONTH
	IF ((MONTH(@FROM_DATE) + @CARRY_FLAG) > MONTH(@TO_DATE) )
	BEGIN
		SET @MY_MONTH = (MONTH(@TO_DATE) + 12) - (MONTH(@FROM_DATE) + @CARRY_FLAG) ;
		SET @CARRY_FLAG = 1 ;		
	END
	ELSE
	BEGIN
		SET @MY_MONTH = MONTH(@TO_DATE) - (MONTH(@FROM_DATE) + @CARRY_FLAG) ;
		SET @CARRY_FLAG = 0 ;
	END ;
	
	--YEAR
	SET @MY_YEAR = YEAR(@TO_DATE) - (YEAR(@FROM_DATE) + @CARRY_FLAG) ;
	
	IF (@OUTPUT_PATTERN = 99)
		SET @RET_STR = dbo.LPAD(@MY_YEAR ,4 ,'0') + '.' + dbo.LPAD(@MY_MONTH ,2 ,'0')  
			+ '.' + dbo.LPAD(@MY_DAY ,2 ,'0') ;
	ELSE
	BEGIN
		SET @RET_STR = '' ;
		IF (@MY_YEAR > 0 )
			SET @RET_STR = CONVERT(VARCHAR(100) ,@MY_YEAR ) + ' Year(s) ' ;
		IF (@MY_MONTH>0)
			SET @RET_STR = @RET_STR + CONVERT(VARCHAR(100) ,@MY_MONTH ) + ' Month(s) ' ;	
		IF (@MY_DAY>0)
			SET @RET_STR = @RET_STR + CONVERT(VARCHAR(100) ,@MY_DAY ) + ' Day(s) ' ;		
	END ;
	
	-- Return the result of the function
	RETURN @RET_STR

END

DELIMITER $$

DROP FUNCTION IF EXISTS `DateSerial` $$
CREATE DEFINER=`root`@`localhost` FUNCTION `DateSerial`(VARYEAR INT ,VARMONTH INT ,VARDAY INT) RETURNS date
BEGIN

  DECLARE TEMPSTR     TEXT ;

  SET TEMPSTR = CONCAT(VARDAY ,' ' ,VARMONTH ,' ' ,VARYEAR) ;

  RETURN STR_TO_DATE( TEMPSTR ,'%d %m %Y') ;

END $$

DELIMITER ;

DELIMITER $$

DROP FUNCTION IF EXISTS `CALC_AGE` $$
CREATE DEFINER=`root`@`localhost` FUNCTION `CALC_AGE`(
  _VAR_FROM_DATE DATE ,_VAR_TO_DATE DATE ,_VAR_OUPUT_PATTERN INT
) RETURNS varchar(100) CHARSET tis620
BEGIN

  DECLARE _RET_STR        VARCHAR(100) DEFAULT '' ;
  DECLARE _FROM_DATE      DATE ;
  DECLARE _TO_DATE        DATE ;
  DECLARE _TEMP_DATE      DATE ;
  DECLARE _CARRY_FLAG     INT DEFAULT 0 ;
  DECLARE _MY_YEAR        INT DEFAULT 0 ;
  DECLARE _MY_MONTH       INT DEFAULT 0 ;
  DECLARE _MY_DAY         INT DEFAULT 0 ;

  -- IN MYSQL GREATER THAN DATE COME FIRST IN DATEDIFF FUNC.
  IF (DATEDIFF(_VAR_TO_DATE ,_VAR_FROM_DATE)>=0) THEN
    BEGIN
      SET _TO_DATE = _VAR_TO_DATE ;
      SET _FROM_DATE = _VAR_FROM_DATE ;
    END ;
  ELSE
    BEGIN
      SET _TO_DATE = _VAR_FROM_DATE ;
      SET _FROM_DATE = _VAR_TO_DATE ;
    END;
  END IF;

  -- DAY CALC
  IF (DAY(_FROM_DATE) > DAY(_TO_DATE)) THEN
    BEGIN
      -- FIND LAST DAY OF THIS MONTH
      SET _TEMP_DATE = DATESERIAL(YEAR(_FROM_DATE) ,MONTH(_fROM_DATE) ,1) ;
      SET _TEMP_DATE = DATE_ADD(_TEMP_DATE ,INTERVAL 1 MONTH) ;
      SET _TEMP_DATE = DATE_ADD(_TEMP_DATE ,INTERVAL -1 DAY) ;

      SET _CARRY_FLAG = DAY(_TEMP_DATE) ;
      SET _MY_DAY = (DAY(_TO_DATE) + _CARRY_FLAG) - DAY(_FROM_DATE) ;
      SET _CARRY_FLAG = 1 ;

    END ;
  ELSE
    SET _MY_DAY = DAY(_TO_DATE) - DAY(_FROM_DATE) ;
  END IF ;

  -- MONTH CALC
  IF ((MONTH(_FROM_DATE) + _CARRY_FLAG) > MONTH(_TO_DATE)) THEN
    BEGIN
      SET _MY_MONTH = (MONTH(_TO_DATE) + 12) - (MONTH(_FROM_DATE) + _CARRY_FLAG) ;
      SET _CARRY_FLAG = 1 ;
    END ;
  ELSE
    BEGIN
      SET _MY_MONTH = MONTH(_TO_DATE) - (MONTH(_FROM_DATE) + _CARRY_FLAG) ;
      SET _CARRY_FLAG = 0 ;
    END ;
  END IF ;

  -- YEAR CALC
  SET _MY_YEAR = YEAR(_TO_DATE) - (YEAR(_FROM_DATE) + _CARRY_FLAG) ;

  CASE _VAR_OUPUT_PATTERN
    WHEN 99 THEN
        SET _RET_STR = CONCAT(LPAD(_MY_YEAR ,4 ,'0') ,'.'
          ,LPAD(_MY_MONTH ,2 ,'0') ,'.'
          ,LPAD(_MY_DAY ,2 ,'0')) ;
    ELSE
      BEGIN
        IF(_MY_YEAR > 0 ) THEN
          SET _RET_STR = CONCAT(FORMAT(_MY_YEAR ,0) ,' Year(s) ') ;
        END IF ;
        IF(_MY_MONTH > 0 ) THEN
          BEGIN
            IF (LENGTH(_RET_STR)>0) THEN
              SET _RET_STR = CONCAT(_RET_STR ,', ') ;
            END IF ;
            SET _RET_STR = CONCAT(_RET_STR ,FORMAT(_MY_MONTH ,0) ,' Month(s) ') ;
          END ;
        END IF ;
        IF(_MY_DAY > 0 ) THEN
          BEGIN
            IF (LENGTH(_RET_STR)>0) THEN
              SET _RET_STR = CONCAT(_RET_STR ,', ') ;
            END IF ;
            SET _RET_STR = CONCAT(_RET_STR ,FORMAT(_MY_DAY ,0) ,' Day(s) ') ;
          END ;
        END IF ;
      END ;
  END CASE ;

  RETURN _RET_STR;

END $$

DELIMITER ;

    public static double DateTimeDiffHours(DateTime sStartDate, DateTime sEndDate)
    {
        try
        {
            TimeSpan s = sEndDate - sStartDate;
            double numberofdays = s.TotalHours;
            return Convert.ToDouble(UtilityCls.DisplayAmount2Decimal(numberofdays.ToString(),false));
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            return 0;
        }
    }

    public static double DateTimeDiffDays(DateTime sStartDate, DateTime sEndDate)
    {
        try
        {
            return (sEndDate.Date - sStartDate.Date).Days;
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            return 0;
        }
    }

DateTime dob = Convert.ToDateTime("18 Feb 1987");
            DateTime PresentYear = DateTime.Now;
            TimeSpan ts = PresentYear - dob;
            DateTime Age = DateTime.MinValue.AddDays(ts.Days);
            MessageBox.Show(string.Format(" {0} Years {1} Month {2} Days", Age.Year - 1, Age.Month - 1, Age.Day - 1));