Fix Bad Date

CREATE FUNCTION [dbo].[ufn_utl_FixBadDate]
(
    @StringDate VARCHAR(12)
)
RETURNS DATE
AS
BEGIN

    DECLARE @DateValue DATE;

    IF LEN(@StringDate) > 1
    BEGIN

        DECLARE @DayDate CHAR(2);
        DECLARE @Month CHAR(2);
        DECLARE @Year VARCHAR(4);

        SET @DayDate = RIGHT('00' + ISNULL(SUBSTRING(@StringDate, 1, CHARINDEX('/', @StringDate) - 1), ''), 2);
        DECLARE @monthYear VARCHAR(100) = SUBSTRING(@StringDate, CHARINDEX('/', @StringDate) + 1, 100);
        SET @Month = RIGHT('00' + ISNULL(SUBSTRING(@monthYear, 1, CHARINDEX('/', @monthYear) - 1), ''), 2);
        SET @Year = RIGHT('20' + ISNULL(SUBSTRING(@monthYear, CHARINDEX('/', @monthYear) + 1, 100), ''), 4);


        SET @DateValue = CONVERT(DATE, @DayDate + '/' + @Month + '/' + @Year, 103);
    END;
    ELSE
    BEGIN
        SET @DateValue = NULL;
    END;

    RETURN (@DateValue);

END;

GO