Question

How do you check if a date is within this or the prior calendar year.

I.E. December 31, This Year > myDate > January 1, Last Year

Answer 1

The standard SQL way is to use EXTRACT:

select *
from t
where extract(year from t.thedate) = extract(year from CURRENT_TIMESTAMP) or
      extract(year from t.thedate) = extract(year from CURRENT_TIMESTAMP) - 1

Not all databases support these functions; but all do have a way of extracting the date somehow. For instance, many support the year function.