Different Sql query for DateFormat

1:To convert 280908(ddmmyy) to 2008-09-28 00:00:00.000

 a- SELECT CONVERT(DATETIME, STUFF(STUFF('280908',3,0,'/'),6,0,'/'), 3)
 b- declare @tst Varchar(6)
     Set @tst = '280908'
     Select cast(substring(@tst,3,2) + '/' + left(@tst,2) + '/' + right(@tst,2) as datetime)

2:Number of weeks between two different dates

SQL :SELECT DATEDIFF (ww, '01/01/1753', '12/31/9999');  

ORACLE:SELECT floor(
             (to_date('12/31/9999','mm/dd/yyyy')
              - to_date('01/01/1753','mm/dd/yyyy')
             )
             / 7) diff
FROM DUAL;