hi, We are planning to install sql 2005 and later we want to upgrade it to sql 2008. Can we use same license(sql 2008) for both SQL 2005 and SQL 2008. if we can use it, how do we need to upgrade(inplace/side-by-side).
Yes, as long as the instance is on the same hardware. You can license 2008 or 2008R2 and have a 2008 and 2005 instance on the same physical box just as you can have multiple instances of the same version. If you are planning to upgrade from 2005 to 2008 on another physical box, you have to license both servers, or do the upgrade really really quick. :)