date conversion

1)To convert the date from 08/01/2008 to 2008/08/01 I used the following code.But I am getting 20/08/0801.Can anybody suggest the best method for this? If possible send the code also.

va_datum = sy-datum.

concatenate va_datum4(4) va_datum0(2) va_datum+2(2) into va_date .

Thanks in advance.

Raghu