Hi Lea Lea,
It's not uncommon for one head of hair to have both oily and dry sections. The oily sections get lank while the dry sections frizz and result in fly-a-way fuzzy strands.
The common opinion is to treat each section of the head differently, isolating the issues independently. As an example, you might use a dry shampoo on the oily roots, but apply a light jojoba or similar oil (almond) on the dry sections.
When you wet wash you would also address each section differently.
To avoid drying out the middle and/or ends you might go ahead and apply a rinse out conditioner from your ears down to your ends while you apply a shampoo product to the roots to address the oily section.
Historically shampoo products designed to address oily hair will sometimes dry out hair. That's the last thing you want for your dry ends. Thus protecting them with a light coating of conditioner.
After finishing with the roots you could wet wash the middle and the ends to achieve a well-balanced head of hair.
Hope that helps.