CREATE FUNCTION [dbo].[FNC_MASK] ( @SRC_STRING VARCHAR(50)
                                 , @PATTERN    VARCHAR(100))
RETURNS NVARCHAR(MAX)
AS
/*
    SELECT DBO.FNC_MASK('20120706145623', '####.##.##')             -- 2012.07.06
    SELECT DBO.FNC_MASK('20120706145623', '####-##-## ##:##:##')    -- 2012-07-06 14:56:23
    SELECT DBO.FNC_MASK('20120706', '####-##-## ##:##:##')          -- 2012-07-06
    SELECT DBO.FNC_MASK(NULL, '####-##-## ##:##:##')                -- NULL
*/
BEGIN
    DECLARE @P_IDX  INT = 0
    ,       @S_IDX  INT = 1

    IF @SRC_STRING IS NULL
        RETURN NULL;

    WHILE CHARINDEX('#', @PATTERN) > 0 AND LEN(SUBSTRING(@SRC_STRING, @S_IDX, 1)) > 0
    BEGIN

        SET @P_IDX = CHARINDEX('#', @PATTERN)
        
        SET @PATTERN = STUFF(@PATTERN, @P_IDX, 1, SUBSTRING(@SRC_STRING, @S_IDX, 1))
        
        SET @S_IDX = @S_IDX + 1

    END

    IF @@ERROR <> 0
            RETURN NULL

    --RETURN REPLACE(@PATTERN, '#', '')
    RETURN LEFT(@PATTERN, @P_IDX)
END
GO

CREATE FUNCTION [dbo].[FNC_FORMAT_DT]  ( @P_DATE       DATETIME
                                       , @P_PATTERN    VARCHAR(100))
RETURNS NVARCHAR(MAX)
AS

/*
    SELECT DBO.FNC_FORMAT_DT(GETDATE(), 'YYYY-MM-DD HH:MI:SS');
    SELECT DBO.FNC_FORMAT_DT(REG_DT, 'YYYYMMDDHHMISS');
*/

BEGIN

    IF @P_DATE IS NULL
        RETURN NULL;

    DECLARE @YYYY    VARCHAR(4)
    ,       @MM      VARCHAR(2)
    ,       @DD      VARCHAR(2)
    ,       @HH      VARCHAR(2)
    ,       @MI      VARCHAR(2)
    ,       @SS      VARCHAR(2);

    SELECT  @YYYY   = SUBSTRING(T.DT,  1, 4)
    ,       @MM     = SUBSTRING(T.DT,  5, 2)
    ,       @DD     = SUBSTRING(T.DT,  7, 2)
    ,       @HH     = SUBSTRING(T.DT,  9, 2)
    ,       @MI     = SUBSTRING(T.DT, 11, 2)
    ,       @SS     = SUBSTRING(T.DT, 13, 2)
    FROM (SELECT FORMAT(ISNULL(@P_DATE, GETDATE()), 'yyyyMMddHHmmss') AS DT) T;

    SET @P_PATTERN = REPLACE(@P_PATTERN, 'YYYY',    @YYYY);
    SET @P_PATTERN = REPLACE(@P_PATTERN, 'MM',      @MM);
    SET @P_PATTERN = REPLACE(@P_PATTERN, 'DD',      @DD);
    SET @P_PATTERN = REPLACE(@P_PATTERN, 'HH',      @HH);
    SET @P_PATTERN = REPLACE(@P_PATTERN, 'MI',      @MI);
    SET @P_PATTERN = REPLACE(@P_PATTERN, 'SS',      @SS);

    IF @@ERROR <> 0
        SET @P_PATTERN = NULL

    RETURN @P_PATTERN;
END