Question on tax deductions on investment properties

[Indigo Dutton]

I know that one can deduct the interest paid on a primary residence's
mortgage from taxable income, so that taxes are not paid on it. Can
anyone tell me whether one can also deduct interest paid on investment
properties, and if whether a property being owner-occupied makes any
difference. If you own a triplex, and live in one unit, can you deduct
the interest paid on the full mortgage for the entire property?

Thanks,
Indigo