Dan,
The several techniques offered will work.
some tips : A stub tenon in the bottom of the post sitting in a mortise cut in the pt 2x12 addresses lateral movement of the post bottom.
Strap hold downs with multiple nails are just plain ugly and I am not a fan of several closely spaced nails along the grain in the post. Use a slightly heavier piece of steel expoxied and lagged into the outside face of the foundation, passing by or going thru the narrow face of the pt 2x12 and then lagged into the outside face of the post with a couple of 3/8 lags spaced about 6" inches apart vertically with the lower one at least 3" up from the post bottom.
deralte