Can we update target table without using update strategy transformation? why?

Yes, we can update the target table by using the session properties.
There are some options in the Session properties.

using :Tu
Targetupdate override.

By using source qualifier transformation to update tha target table,through SQL overriding...

Step 1: Go to session , and in treat source rows as :UPDATE
step2: in target table option select INSERT and UPDATE ELSE INSERT :)
Step 3:Refresh and Run the session .