fnFormatDate

MS SQL Server 的T-SQL 真的不好用，連TO_CHAR都沒有。
我自己寫了一個function，供MS SQL Server使用

用法
select dbo.fnFormatDate(getdate(),'yyyymmddHHMISS')
----------------------------------------------------------------------------------------------------------------------------------
drop FUNCTION dbo.fnFormatDate

CREATE FUNCTION dbo.fnFormatDate (@Datetime DATETIME, @FormatMask VARCHAR(32))
RETURNS VARCHAR(32)
AS
BEGIN
    DECLARE @StringDate VARCHAR(32)
    SET @StringDate = @FormatMask
    IF (CHARINDEX ('HH',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'HH',
                                     DATENAME(HH, @Datetime))
    IF (CHARINDEX ('MI',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'MI',
                                     DATENAME(MI, @Datetime))
    IF (CHARINDEX ('SS',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'SS',
                                     DATENAME(SS, @Datetime))

    IF (CHARINDEX ('YYYY',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'YYYY',
                         DATENAME(YY, @Datetime))
    IF (CHARINDEX ('YY',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'YY',
                         RIGHT(DATENAME(YY, @Datetime),2))
    IF (CHARINDEX ('Month',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'Month',
                         DATENAME(MM, @Datetime))
    IF (CHARINDEX ('MON',@StringDate COLLATE SQL_Latin1_General_CP1_CS_AS)>0)
       SET @StringDate = REPLACE(@StringDate, 'MON',
                         LEFT(UPPER(DATENAME(MM, @Datetime)),3))
    IF (CHARINDEX ('Mon',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'Mon',
                                     LEFT(DATENAME(MM, @Datetime),3))
    IF (CHARINDEX ('MM',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'MM',
                  RIGHT('0'+CONVERT(VARCHAR,DATEPART(MM, @Datetime)),2))
    IF (CHARINDEX ('M',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'M',
                         CONVERT(VARCHAR,DATEPART(MM, @Datetime)))
    IF (CHARINDEX ('DD',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'DD',
                         RIGHT('0'+DATENAME(DD, @Datetime),2))
    IF (CHARINDEX ('D',@StringDate) > 0)
       SET @StringDate = REPLACE(@StringDate, 'D',
                                     DATENAME(DD, @Datetime))  
  
RETURN @StringDate
END