SQLite: How to calculate age from birth date

Question

What is the best way to calculate the age in years from a birth date in sqlite3?

Answer 1

To get @Bruno Costa's answer to work I had to add brackets around the strftime difference calculation on the 4th line and reverse the comparison to 'now' to be less than or equal: as I understand it the calculation is working out whether the calculated date is before or after today. If the calculated date is today or earlier then the birthday has already been this year or is today:

select
    case
        when date(dob, '+' ||
            (strftime('%Y', 'now') - strftime('%Y', dob)) ||
            ' years') <= date('now')
        then strftime('%Y', 'now') - strftime('%Y', dob)
        else strftime('%Y', 'now') - strftime('%Y', dob) - 1
    end
    as age
from t;

Note that the solution linked to in @Bruno Costa's answer was untested.